- Intro section that links to how this is exposed to userspace.
- Lots more hyperlinks.
- Minor clarifications and style polish
Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: Gustavo Padovan <gustavo(a)padovan.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
Documentation/driver-api/dma-buf.rst | 6 ++
drivers/dma-buf/dma-fence.c | 140 ++++++++++++++++++---------
2 files changed, 102 insertions(+), 44 deletions(-)
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index dc384f2f7f34..b541e97c7ab1 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -130,6 +130,12 @@ Reservation Objects
DMA Fences
----------
+.. kernel-doc:: drivers/dma-buf/dma-fence.c
+ :doc: DMA fences overview
+
+DMA Fences Functions Reference
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
.. kernel-doc:: drivers/dma-buf/dma-fence.c
:export:
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 41ec19c9efc7..0387c6a59055 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -38,12 +38,43 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
*/
static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
+/**
+ * DOC: DMA fences overview
+ *
+ * DMA fences, represented by &struct dma_fence, are the kernel internal
+ * synchronization primitive for DMA operations like GPU rendering, video
+ * encoding/decoding, or displaying buffers on a screen.
+ *
+ * A fence is initialized using dma_fence_init() and completed using
+ * dma_fence_signal(). Fences are associated with a context, allocated through
+ * dma_fence_context_alloc(), and all fences on the same context are
+ * fully ordered.
+ *
+ * Since the purposes of fences is to facilitate cross-device and
+ * cross-application synchronization, there's multiple ways to use one:
+ *
+ * - Individual fences can be exposed as a &sync_file, accessed as a file
+ * descriptor from userspace, created by calling sync_file_create(). This is
+ * called explicit fencing, since userspace passes around explicit
+ * synchronization points.
+ *
+ * - Some subsystems also have their own explicit fencing primitives, like
+ * &drm_syncobj. Compared to &sync_file, a &drm_syncobj allows the underlying
+ * fence to be updated.
+ *
+ * - Then there's also implicit fencing, where the synchronization points are
+ * implicitly passed around as part of shared &dma_buf instances. Such
+ * implicit fences are stored in &struct reservation_object through the
+ * &dma_buf.resv pointer.
+ */
+
/**
* dma_fence_context_alloc - allocate an array of fence contexts
- * @num: [in] amount of contexts to allocate
+ * @num: amount of contexts to allocate
*
- * This function will return the first index of the number of fences allocated.
- * The fence context is used for setting fence->context to a unique number.
+ * This function will return the first index of the number of fence contexts
+ * allocated. The fence context is used for setting &dma_fence.context to a
+ * unique number by passing the context to dma_fence_init().
*/
u64 dma_fence_context_alloc(unsigned num)
{
@@ -59,10 +90,14 @@ EXPORT_SYMBOL(dma_fence_context_alloc);
* Signal completion for software callbacks on a fence, this will unblock
* dma_fence_wait() calls and run all the callbacks added with
* dma_fence_add_callback(). Can be called multiple times, but since a fence
- * can only go from unsignaled to signaled state, it will only be effective
- * the first time.
+ * can only go from the unsignaled to the signaled state and not back, it will
+ * only be effective the first time.
*
- * Unlike dma_fence_signal, this function must be called with fence->lock held.
+ * Unlike dma_fence_signal(), this function must be called with &dma_fence.lock
+ * held.
+ *
+ * Returns 0 on success and a negative error value when @fence has been
+ * signalled already.
*/
int dma_fence_signal_locked(struct dma_fence *fence)
{
@@ -102,8 +137,11 @@ EXPORT_SYMBOL(dma_fence_signal_locked);
* Signal completion for software callbacks on a fence, this will unblock
* dma_fence_wait() calls and run all the callbacks added with
* dma_fence_add_callback(). Can be called multiple times, but since a fence
- * can only go from unsignaled to signaled state, it will only be effective
- * the first time.
+ * can only go from the unsignaled to the signaled state and not back, it will
+ * only be effective the first time.
+ *
+ * Returns 0 on success and a negative error value when @fence has been
+ * signalled already.
*/
int dma_fence_signal(struct dma_fence *fence)
{
@@ -136,9 +174,9 @@ EXPORT_SYMBOL(dma_fence_signal);
/**
* dma_fence_wait_timeout - sleep until the fence gets signaled
* or until timeout elapses
- * @fence: [in] the fence to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @fence: the fence to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
*
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
* remaining timeout in jiffies on success. Other error values may be
@@ -148,6 +186,8 @@ EXPORT_SYMBOL(dma_fence_signal);
* directly or indirectly (buf-mgr between reservation and committing)
* holds a reference to the fence, otherwise the fence might be
* freed before return, resulting in undefined behavior.
+ *
+ * See also dma_fence_wait() and dma_fence_wait_any_timeout().
*/
signed long
dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
@@ -167,6 +207,13 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
}
EXPORT_SYMBOL(dma_fence_wait_timeout);
+/**
+ * dma_fence_release - default relese function for fences
+ * @kref: &dma_fence.recfount
+ *
+ * This is the default release functions for &dma_fence. Drivers shouldn't call
+ * this directly, but instead call dma_fence_put().
+ */
void dma_fence_release(struct kref *kref)
{
struct dma_fence *fence =
@@ -199,10 +246,11 @@ EXPORT_SYMBOL(dma_fence_free);
/**
* dma_fence_enable_sw_signaling - enable signaling on fence
- * @fence: [in] the fence to enable
+ * @fence: the fence to enable
*
- * this will request for sw signaling to be enabled, to make the fence
- * complete as soon as possible
+ * This will request for sw signaling to be enabled, to make the fence
+ * complete as soon as possible. This calls &dma_fence_ops.enable_signaling
+ * internally.
*/
void dma_fence_enable_sw_signaling(struct dma_fence *fence)
{
@@ -226,24 +274,24 @@ EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
/**
* dma_fence_add_callback - add a callback to be called when the fence
* is signaled
- * @fence: [in] the fence to wait on
- * @cb: [in] the callback to register
- * @func: [in] the function to call
+ * @fence: the fence to wait on
+ * @cb: the callback to register
+ * @func: the function to call
*
- * cb will be initialized by dma_fence_add_callback, no initialization
+ * @cb will be initialized by dma_fence_add_callback(), no initialization
* by the caller is required. Any number of callbacks can be registered
* to a fence, but a callback can only be registered to one fence at a time.
*
* Note that the callback can be called from an atomic context. If
* fence is already signaled, this function will return -ENOENT (and
- * *not* call the callback)
+ * *not* call the callback).
*
* Add a software callback to the fence. Same restrictions apply to
- * refcount as it does to dma_fence_wait, however the caller doesn't need to
- * keep a refcount to fence afterwards: when software access is enabled,
- * the creator of the fence is required to keep the fence alive until
- * after it signals with dma_fence_signal. The callback itself can be called
- * from irq context.
+ * refcount as it does to dma_fence_wait(), however the caller doesn't need to
+ * keep a refcount to fence afterward dma_fence_add_callback() has returned:
+ * when software access is enabled, the creator of the fence is required to keep
+ * the fence alive until after it signals with dma_fence_signal(). The callback
+ * itself can be called from irq context.
*
* Returns 0 in case of success, -ENOENT if the fence is already signaled
* and -EINVAL in case of error.
@@ -292,7 +340,7 @@ EXPORT_SYMBOL(dma_fence_add_callback);
/**
* dma_fence_get_status - returns the status upon completion
- * @fence: [in] the dma_fence to query
+ * @fence: the dma_fence to query
*
* This wraps dma_fence_get_status_locked() to return the error status
* condition on a signaled fence. See dma_fence_get_status_locked() for more
@@ -317,8 +365,8 @@ EXPORT_SYMBOL(dma_fence_get_status);
/**
* dma_fence_remove_callback - remove a callback from the signaling list
- * @fence: [in] the fence to wait on
- * @cb: [in] the callback to remove
+ * @fence: the fence to wait on
+ * @cb: the callback to remove
*
* Remove a previously queued callback from the fence. This function returns
* true if the callback is successfully removed, or false if the fence has
@@ -329,6 +377,9 @@ EXPORT_SYMBOL(dma_fence_get_status);
* doing, since deadlocks and race conditions could occur all too easily. For
* this reason, it should only ever be done on hardware lockup recovery,
* with a reference held to the fence.
+ *
+ * Behaviour is undefined if @cb has not been added to @fence using
+ * dma_fence_add_callback() beforehand.
*/
bool
dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
@@ -365,9 +416,9 @@ dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
/**
* dma_fence_default_wait - default sleep until the fence gets signaled
* or until timeout elapses
- * @fence: [in] the fence to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @fence: the fence to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
*
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
* remaining timeout in jiffies on success. If timeout is zero the value one is
@@ -460,12 +511,12 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
/**
* dma_fence_wait_any_timeout - sleep until any fence gets signaled
* or until timeout elapses
- * @fences: [in] array of fences to wait on
- * @count: [in] number of fences to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
- * @idx: [out] the first signaled fence index, meaningful only on
- * positive return
+ * @fences: array of fences to wait on
+ * @count: number of fences to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @idx: used to store the first signaled fence index, meaningful only on
+ * positive return
*
* Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
* interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
@@ -474,6 +525,8 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
* Synchronous waits for the first fence in the array to be signaled. The
* caller needs to hold a reference to all fences in the array, otherwise a
* fence might be freed before return, resulting in undefined behavior.
+ *
+ * See also dma_fence_wait() and dma_fence_wait_timeout().
*/
signed long
dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
@@ -546,19 +599,18 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
/**
* dma_fence_init - Initialize a custom fence.
- * @fence: [in] the fence to initialize
- * @ops: [in] the dma_fence_ops for operations on this fence
- * @lock: [in] the irqsafe spinlock to use for locking this fence
- * @context: [in] the execution context this fence is run on
- * @seqno: [in] a linear increasing sequence number for this context
+ * @fence: the fence to initialize
+ * @ops: the dma_fence_ops for operations on this fence
+ * @lock: the irqsafe spinlock to use for locking this fence
+ * @context: the execution context this fence is run on
+ * @seqno: a linear increasing sequence number for this context
*
* Initializes an allocated fence, the caller doesn't have to keep its
* refcount after committing with this fence, but it will need to hold a
- * refcount again if dma_fence_ops.enable_signaling gets called. This can
- * be used for other implementing other types of fence.
+ * refcount again if &dma_fence_ops.enable_signaling gets called.
*
* context and seqno are used for easy comparison between fences, allowing
- * to check which fence is later by simply using dma_fence_later.
+ * to check which fence is later by simply using dma_fence_later().
*/
void
dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
--
2.17.0
Use this function to set an sg entry to point to device resources mapped
using dma_map_resource(). The page pointer is set to NULL and only the DMA
address, length and offset values are valid.
Signed-off-by: Christian König <christian.koenig(a)amd.com>
---
include/linux/scatterlist.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 22b2131bcdcd..f944ee4e482c 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -149,6 +149,29 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
}
+/**
+ * sg_set_dma_addr - Set sg entry to point at specified dma address
+ * @sg: SG entry
+ * @address: DMA address to set
+ * @len: Length of data
+ * @offset: Offset into page
+ *
+ * Description:
+ * Use this function to set an sg entry to point to device resources mapped
+ * using dma_map_resource(). The page pointer is set to NULL and only the DMA
+ * address, length and offset values are valid.
+ *
+ **/
+static inline void sg_set_dma_addr(struct scatterlist *sg, dma_addr_t address,
+ unsigned int len, unsigned int offset)
+{
+ sg_set_page(sg, NULL, len, offset);
+ sg->dma_address = address;
+#ifdef CONFIG_NEED_SG_DMA_LENGTH
+ sg->dma_length = len;
+#endif
+}
+
/*
* Loop over each sg element, following the pointer to a new list if necessary
*/
--
2.14.1
When this was introduced in
commit a519435a96597d8cd96123246fea4ae5a6c90b02
Author: Christian König <christian.koenig(a)amd.com>
Date: Tue Oct 20 16:34:16 2015 +0200
dma-buf/fence: add fence_wait_any_timeout function v2
there was a restriction added that this only works if the dma-fence
uses the dma_fence_default_wait hook. Which works for amdgpu, which is
the only caller. Well, until you share some buffers with e.g. i915,
then you get an -EINVAL.
But there's really no reason for this, because all drivers must
support callbacks. The special ->wait hook is only as an optimization;
if the driver needs to create a worker thread for an active callback,
then it can avoid to do that if it knows that there's a process
context available already. So ->wait is just an optimization, just
using the logic in dma_fence_default_wait() should work for all
drivers.
Let's remove this restriction.
Reviewed-by: Christian König <christian.koenig(a)amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: Gustavo Padovan <gustavo(a)padovan.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
Cc: Christian König <christian.koenig(a)amd.com>
Cc: Alex Deucher <alexander.deucher(a)amd.com>
---
drivers/dma-buf/dma-fence.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 7b5b40d6b70e..59049375bd19 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -503,11 +503,6 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
for (i = 0; i < count; ++i) {
struct dma_fence *fence = fences[i];
- if (fence->ops->wait != dma_fence_default_wait) {
- ret = -EINVAL;
- goto fence_rm_cb;
- }
-
cb[i].task = current;
if (dma_fence_add_callback(fence, &cb[i].base,
dma_fence_default_wait_cb)) {
--
2.17.0
On Mon, Apr 30, 2018 at 10:49:00AM -0700, Eric Anholt wrote:
> Daniel Vetter <daniel.vetter(a)ffwll.ch> writes:
> > + /**
> > + * @fill_driver_data:
> > + *
> > + * Callback to fill in free-form debug info Returns amount of bytes
> > + * filled, or negative error on failure.
>
> Maybe this "Returns" should be on a new line? Or at least a '.' in
> between.
Indeed I've missed this, thanks for spotting it. Done both&applied.
Thanks, Daniel
>
> Other than that,
>
> Reviewed-by: Eric Anholt <eric(a)anholt.net>
>
> Thanks!
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
When this was introduced in
commit a519435a96597d8cd96123246fea4ae5a6c90b02
Author: Christian König <christian.koenig(a)amd.com>
Date: Tue Oct 20 16:34:16 2015 +0200
dma-buf/fence: add fence_wait_any_timeout function v2
there was a restriction added that this only works if the dma-fence
uses the dma_fence_default_wait hook. Which works for amdgpu, which is
the only caller. Well, until you share some buffers with e.g. i915,
then you get an -EINVAL.
But there's really no reason for this, because all drivers must
support callbacks. The special ->wait hook is only as an optimization;
if the driver needs to create a worker thread for an active callback,
then it can avoid to do that if it knows that there's a process
context available already. So ->wait is just an optimization, just
using the logic in dma_fence_default_wait() should work for all
drivers.
Let's remove this restriction.
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: Gustavo Padovan <gustavo(a)padovan.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
Cc: Christian König <christian.koenig(a)amd.com>
Cc: Alex Deucher <alexander.deucher(a)amd.com>
---
drivers/dma-buf/dma-fence.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 7b5b40d6b70e..59049375bd19 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -503,11 +503,6 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
for (i = 0; i < count; ++i) {
struct dma_fence *fence = fences[i];
- if (fence->ops->wait != dma_fence_default_wait) {
- ret = -EINVAL;
- goto fence_rm_cb;
- }
-
cb[i].task = current;
if (dma_fence_add_callback(fence, &cb[i].base,
dma_fence_default_wait_cb)) {
--
2.17.0
- Intro section that links to how this is exposed to userspace.
- Lots more hyperlinks.
- Minor clarifications and style polish
Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: Gustavo Padovan <gustavo(a)padovan.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
Documentation/driver-api/dma-buf.rst | 6 ++
drivers/dma-buf/dma-fence.c | 140 ++++++++++++++++++---------
2 files changed, 102 insertions(+), 44 deletions(-)
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index dc384f2f7f34..b541e97c7ab1 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -130,6 +130,12 @@ Reservation Objects
DMA Fences
----------
+.. kernel-doc:: drivers/dma-buf/dma-fence.c
+ :doc: DMA fences overview
+
+DMA Fences Functions Reference
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
.. kernel-doc:: drivers/dma-buf/dma-fence.c
:export:
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 30fcbe415ff4..4e931e1de198 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -38,12 +38,43 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal);
*/
static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0);
+/**
+ * DOC: DMA fences overview
+ *
+ * DMA fences, represented by &struct dma_fence, are the kernel internal
+ * synchronization primitive for DMA operations like GPU rendering, video
+ * encoding/decoding, or displaying buffers on a screen.
+ *
+ * A fence is initialized using dma_fence_init() and completed using
+ * dma_fence_signal(). Fences are associated with a context, allocated through
+ * dma_fence_context_alloc(), and all fences on the same context are
+ * fully ordered.
+ *
+ * Since the purposes of fences is to facilitate cross-device and
+ * cross-application synchronization, there's multiple ways to use one:
+ *
+ * - Individual fences can be exposed as a &sync_file, accessed as a file
+ * descriptor from userspace, created by calling sync_file_create(). This is
+ * called explicit fencing, since userspace passes around explicit
+ * synchronization points.
+ *
+ * - Some subsystems also have their own explicit fencing primitives, like
+ * &drm_syncobj. Compared to &sync_file, a &drm_syncobj allows the underlying
+ * fence to be updated.
+ *
+ * - Then there's also implicit fencing, where the synchronization points are
+ * implicitly passed around as part of shared &dma_buf instances. Such
+ * implicit fences are stored in &struct reservation_object through the
+ * &dma_buf.resv pointer.
+ */
+
/**
* dma_fence_context_alloc - allocate an array of fence contexts
- * @num: [in] amount of contexts to allocate
+ * @num: amount of contexts to allocate
*
- * This function will return the first index of the number of fences allocated.
- * The fence context is used for setting fence->context to a unique number.
+ * This function will return the first index of the number of fence contexts
+ * allocated. The fence context is used for setting &dma_fence.context to a
+ * unique number by passing the context to dma_fence_init().
*/
u64 dma_fence_context_alloc(unsigned num)
{
@@ -59,10 +90,14 @@ EXPORT_SYMBOL(dma_fence_context_alloc);
* Signal completion for software callbacks on a fence, this will unblock
* dma_fence_wait() calls and run all the callbacks added with
* dma_fence_add_callback(). Can be called multiple times, but since a fence
- * can only go from unsignaled to signaled state, it will only be effective
- * the first time.
+ * can only go from the unsignaled to the signaled state and not back, it will
+ * only be effective the first time.
*
- * Unlike dma_fence_signal, this function must be called with fence->lock held.
+ * Unlike dma_fence_signal(), this function must be called with &dma_fence.lock
+ * held.
+ *
+ * Returns 0 on success and a negative error value when @fence has been
+ * signalled already.
*/
int dma_fence_signal_locked(struct dma_fence *fence)
{
@@ -102,8 +137,11 @@ EXPORT_SYMBOL(dma_fence_signal_locked);
* Signal completion for software callbacks on a fence, this will unblock
* dma_fence_wait() calls and run all the callbacks added with
* dma_fence_add_callback(). Can be called multiple times, but since a fence
- * can only go from unsignaled to signaled state, it will only be effective
- * the first time.
+ * can only go from the unsignaled to the signaled state and not back, it will
+ * only be effective the first time.
+ *
+ * Returns 0 on success and a negative error value when @fence has been
+ * signalled already.
*/
int dma_fence_signal(struct dma_fence *fence)
{
@@ -136,9 +174,9 @@ EXPORT_SYMBOL(dma_fence_signal);
/**
* dma_fence_wait_timeout - sleep until the fence gets signaled
* or until timeout elapses
- * @fence: [in] the fence to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @fence: the fence to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
*
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
* remaining timeout in jiffies on success. Other error values may be
@@ -148,6 +186,8 @@ EXPORT_SYMBOL(dma_fence_signal);
* directly or indirectly (buf-mgr between reservation and committing)
* holds a reference to the fence, otherwise the fence might be
* freed before return, resulting in undefined behavior.
+ *
+ * See also dma_fence_wait() and dma_fence_wait_any_timeout().
*/
signed long
dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
@@ -167,6 +207,13 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
}
EXPORT_SYMBOL(dma_fence_wait_timeout);
+/**
+ * dma_fence_release - default relese function for fences
+ * @kref: &dma_fence.recfount
+ *
+ * This is the default release functions for &dma_fence. Drivers shouldn't call
+ * this directly, but instead call dma_fence_put().
+ */
void dma_fence_release(struct kref *kref)
{
struct dma_fence *fence =
@@ -199,10 +246,11 @@ EXPORT_SYMBOL(dma_fence_free);
/**
* dma_fence_enable_sw_signaling - enable signaling on fence
- * @fence: [in] the fence to enable
+ * @fence: the fence to enable
*
- * this will request for sw signaling to be enabled, to make the fence
- * complete as soon as possible
+ * This will request for sw signaling to be enabled, to make the fence
+ * complete as soon as possible. This calls &dma_fence_ops.enable_signaling
+ * internally.
*/
void dma_fence_enable_sw_signaling(struct dma_fence *fence)
{
@@ -226,24 +274,24 @@ EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
/**
* dma_fence_add_callback - add a callback to be called when the fence
* is signaled
- * @fence: [in] the fence to wait on
- * @cb: [in] the callback to register
- * @func: [in] the function to call
+ * @fence: the fence to wait on
+ * @cb: the callback to register
+ * @func: the function to call
*
- * cb will be initialized by dma_fence_add_callback, no initialization
+ * @cb will be initialized by dma_fence_add_callback(), no initialization
* by the caller is required. Any number of callbacks can be registered
* to a fence, but a callback can only be registered to one fence at a time.
*
* Note that the callback can be called from an atomic context. If
* fence is already signaled, this function will return -ENOENT (and
- * *not* call the callback)
+ * *not* call the callback).
*
* Add a software callback to the fence. Same restrictions apply to
- * refcount as it does to dma_fence_wait, however the caller doesn't need to
- * keep a refcount to fence afterwards: when software access is enabled,
- * the creator of the fence is required to keep the fence alive until
- * after it signals with dma_fence_signal. The callback itself can be called
- * from irq context.
+ * refcount as it does to dma_fence_wait(), however the caller doesn't need to
+ * keep a refcount to fence afterward dma_fence_add_callback() has returned:
+ * when software access is enabled, the creator of the fence is required to keep
+ * the fence alive until after it signals with dma_fence_signal(). The callback
+ * itself can be called from irq context.
*
* Returns 0 in case of success, -ENOENT if the fence is already signaled
* and -EINVAL in case of error.
@@ -292,7 +340,7 @@ EXPORT_SYMBOL(dma_fence_add_callback);
/**
* dma_fence_get_status - returns the status upon completion
- * @fence: [in] the dma_fence to query
+ * @fence: the dma_fence to query
*
* This wraps dma_fence_get_status_locked() to return the error status
* condition on a signaled fence. See dma_fence_get_status_locked() for more
@@ -317,8 +365,8 @@ EXPORT_SYMBOL(dma_fence_get_status);
/**
* dma_fence_remove_callback - remove a callback from the signaling list
- * @fence: [in] the fence to wait on
- * @cb: [in] the callback to remove
+ * @fence: the fence to wait on
+ * @cb: the callback to remove
*
* Remove a previously queued callback from the fence. This function returns
* true if the callback is successfully removed, or false if the fence has
@@ -329,6 +377,9 @@ EXPORT_SYMBOL(dma_fence_get_status);
* doing, since deadlocks and race conditions could occur all too easily. For
* this reason, it should only ever be done on hardware lockup recovery,
* with a reference held to the fence.
+ *
+ * Behaviour is undefined if @cb has not been added to @fence using
+ * dma_fence_add_callback() beforehand.
*/
bool
dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb)
@@ -365,9 +416,9 @@ dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
/**
* dma_fence_default_wait - default sleep until the fence gets signaled
* or until timeout elapses
- * @fence: [in] the fence to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @fence: the fence to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
*
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the
* remaining timeout in jiffies on success. If timeout is zero the value one is
@@ -460,12 +511,12 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
/**
* dma_fence_wait_any_timeout - sleep until any fence gets signaled
* or until timeout elapses
- * @fences: [in] array of fences to wait on
- * @count: [in] number of fences to wait on
- * @intr: [in] if true, do an interruptible wait
- * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
- * @idx: [out] the first signaled fence index, meaningful only on
- * positive return
+ * @fences: array of fences to wait on
+ * @count: number of fences to wait on
+ * @intr: if true, do an interruptible wait
+ * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT
+ * @idx: used to store the first signaled fence index, meaningful only on
+ * positive return
*
* Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if
* interrupted, 0 if the wait timed out, or the remaining timeout in jiffies
@@ -474,6 +525,8 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
* Synchronous waits for the first fence in the array to be signaled. The
* caller needs to hold a reference to all fences in the array, otherwise a
* fence might be freed before return, resulting in undefined behavior.
+ *
+ * See also dma_fence_wait() and dma_fence_wait_timeout().
*/
signed long
dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
@@ -546,19 +599,18 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout);
/**
* dma_fence_init - Initialize a custom fence.
- * @fence: [in] the fence to initialize
- * @ops: [in] the dma_fence_ops for operations on this fence
- * @lock: [in] the irqsafe spinlock to use for locking this fence
- * @context: [in] the execution context this fence is run on
- * @seqno: [in] a linear increasing sequence number for this context
+ * @fence: the fence to initialize
+ * @ops: the dma_fence_ops for operations on this fence
+ * @lock: the irqsafe spinlock to use for locking this fence
+ * @context: the execution context this fence is run on
+ * @seqno: a linear increasing sequence number for this context
*
* Initializes an allocated fence, the caller doesn't have to keep its
* refcount after committing with this fence, but it will need to hold a
- * refcount again if dma_fence_ops.enable_signaling gets called. This can
- * be used for other implementing other types of fence.
+ * refcount again if &dma_fence_ops.enable_signaling gets called.
*
* context and seqno are used for easy comparison between fences, allowing
- * to check which fence is later by simply using dma_fence_later.
+ * to check which fence is later by simply using dma_fence_later().
*/
void
dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
--
2.17.0
Almost everyone uses dma_fence_default_wait.
Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: Gustavo Padovan <gustavo(a)padovan.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
drivers/dma-buf/dma-fence-array.c | 1 -
drivers/dma-buf/dma-fence.c | 5 ++++-
drivers/dma-buf/sw_sync.c | 1 -
include/linux/dma-fence.h | 13 ++++++++-----
4 files changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index dd1edfb27b61..a8c254497251 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -104,7 +104,6 @@ const struct dma_fence_ops dma_fence_array_ops = {
.get_timeline_name = dma_fence_array_get_timeline_name,
.enable_signaling = dma_fence_array_enable_signaling,
.signaled = dma_fence_array_signaled,
- .wait = dma_fence_default_wait,
.release = dma_fence_array_release,
};
EXPORT_SYMBOL(dma_fence_array_ops);
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 59049375bd19..30fcbe415ff4 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -158,7 +158,10 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
return -EINVAL;
trace_dma_fence_wait_start(fence);
- ret = fence->ops->wait(fence, intr, timeout);
+ if (fence->ops->wait)
+ ret = fence->ops->wait(fence, intr, timeout);
+ else
+ ret = dma_fence_default_wait(fence, intr, timeout);
trace_dma_fence_wait_end(fence);
return ret;
}
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
index 3d78ca89a605..53c1d6d36a64 100644
--- a/drivers/dma-buf/sw_sync.c
+++ b/drivers/dma-buf/sw_sync.c
@@ -188,7 +188,6 @@ static const struct dma_fence_ops timeline_fence_ops = {
.get_timeline_name = timeline_fence_get_timeline_name,
.enable_signaling = timeline_fence_enable_signaling,
.signaled = timeline_fence_signaled,
- .wait = dma_fence_default_wait,
.release = timeline_fence_release,
.fence_value_str = timeline_fence_value_str,
.timeline_value_str = timeline_fence_timeline_value_str,
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index c730f569621a..d05496ff0d10 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -191,11 +191,14 @@ struct dma_fence_ops {
/**
* @wait:
*
- * Custom wait implementation, or dma_fence_default_wait.
+ * Custom wait implementation, defaults to dma_fence_default_wait() if
+ * not set.
*
- * Must not be NULL, set to dma_fence_default_wait for default implementation.
- * the dma_fence_default_wait implementation should work for any fence, as long
- * as enable_signaling works correctly.
+ * The dma_fence_default_wait implementation should work for any fence, as long
+ * as @enable_signaling works correctly. This hook allows drivers to
+ * have an optimized version for the case where a process context is
+ * already available, e.g. if @enable_signaling for the general case
+ * needs to set up a worker thread.
*
* Must return -ERESTARTSYS if the wait is intr = true and the wait was
* interrupted, and remaining jiffies if fence has signaled, or 0 if wait
@@ -203,7 +206,7 @@ struct dma_fence_ops {
* which should be treated as if the fence is signaled. For example a hardware
* lockup could be reported like that.
*
- * This callback is mandatory.
+ * This callback is optional.
*/
signed long (*wait)(struct dma_fence *fence,
bool intr, signed long timeout);
--
2.17.0
- Switch to inline member docs for dma_fence_ops.
- Mild polish all around.
- hyperlink all the things!
v2: - Remove the various [in] annotations, they seem really uncommon
in kerneldoc and look funny.
Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
---
include/linux/dma-fence.h | 235 +++++++++++++++++++++++++-------------
1 file changed, 154 insertions(+), 81 deletions(-)
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 4c008170fe65..9d6f39bf2111 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -94,11 +94,11 @@ typedef void (*dma_fence_func_t)(struct dma_fence *fence,
struct dma_fence_cb *cb);
/**
- * struct dma_fence_cb - callback for dma_fence_add_callback
- * @node: used by dma_fence_add_callback to append this struct to fence::cb_list
+ * struct dma_fence_cb - callback for dma_fence_add_callback()
+ * @node: used by dma_fence_add_callback() to append this struct to fence::cb_list
* @func: dma_fence_func_t to call
*
- * This struct will be initialized by dma_fence_add_callback, additional
+ * This struct will be initialized by dma_fence_add_callback(), additional
* data can be passed along by embedding dma_fence_cb in another struct.
*/
struct dma_fence_cb {
@@ -108,75 +108,142 @@ struct dma_fence_cb {
/**
* struct dma_fence_ops - operations implemented for fence
- * @get_driver_name: returns the driver name.
- * @get_timeline_name: return the name of the context this fence belongs to.
- * @enable_signaling: enable software signaling of fence.
- * @signaled: [optional] peek whether the fence is signaled, can be null.
- * @wait: custom wait implementation, or dma_fence_default_wait.
- * @release: [optional] called on destruction of fence, can be null
- * @fill_driver_data: [optional] callback to fill in free-form debug info
- * Returns amount of bytes filled, or -errno.
- * @fence_value_str: [optional] fills in the value of the fence as a string
- * @timeline_value_str: [optional] fills in the current value of the timeline
- * as a string
*
- * Notes on enable_signaling:
- * For fence implementations that have the capability for hw->hw
- * signaling, they can implement this op to enable the necessary
- * irqs, or insert commands into cmdstream, etc. This is called
- * in the first wait() or add_callback() path to let the fence
- * implementation know that there is another driver waiting on
- * the signal (ie. hw->sw case).
- *
- * This function can be called from atomic context, but not
- * from irq context, so normal spinlocks can be used.
- *
- * A return value of false indicates the fence already passed,
- * or some failure occurred that made it impossible to enable
- * signaling. True indicates successful enabling.
- *
- * fence->error may be set in enable_signaling, but only when false is
- * returned.
- *
- * Calling dma_fence_signal before enable_signaling is called allows
- * for a tiny race window in which enable_signaling is called during,
- * before, or after dma_fence_signal. To fight this, it is recommended
- * that before enable_signaling returns true an extra reference is
- * taken on the fence, to be released when the fence is signaled.
- * This will mean dma_fence_signal will still be called twice, but
- * the second time will be a noop since it was already signaled.
- *
- * Notes on signaled:
- * May set fence->error if returning true.
- *
- * Notes on wait:
- * Must not be NULL, set to dma_fence_default_wait for default implementation.
- * the dma_fence_default_wait implementation should work for any fence, as long
- * as enable_signaling works correctly.
- *
- * Must return -ERESTARTSYS if the wait is intr = true and the wait was
- * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
- * timed out. Can also return other error values on custom implementations,
- * which should be treated as if the fence is signaled. For example a hardware
- * lockup could be reported like that.
- *
- * Notes on release:
- * Can be NULL, this function allows additional commands to run on
- * destruction of the fence. Can be called from irq context.
- * If pointer is set to NULL, kfree will get called instead.
*/
-
struct dma_fence_ops {
+ /**
+ * @get_driver_name:
+ *
+ * Returns the driver name. This is a callback to allow drivers to
+ * compute the name at runtime, without having it to store permanently
+ * for each fence, or build a cache of some sort.
+ *
+ * This callback is mandatory.
+ */
const char * (*get_driver_name)(struct dma_fence *fence);
+
+ /**
+ * @get_timeline_name:
+ *
+ * Return the name of the context this fence belongs to. This is a
+ * callback to allow drivers to compute the name at runtime, without
+ * having it to store permanently for each fence, or build a cache of
+ * some sort.
+ *
+ * This callback is mandatory.
+ */
const char * (*get_timeline_name)(struct dma_fence *fence);
+
+ /**
+ * @enable_signaling:
+ *
+ * Enable software signaling of fence.
+ *
+ * For fence implementations that have the capability for hw->hw
+ * signaling, they can implement this op to enable the necessary
+ * interrupts, or insert commands into cmdstream, etc, to avoid these
+ * costly operations for the common case where only hw->hw
+ * synchronization is required. This is called in the first
+ * dma_fence_wait() or dma_fence_add_callback() path to let the fence
+ * implementation know that there is another driver waiting on the
+ * signal (ie. hw->sw case).
+ *
+ * This function can be called from atomic context, but not
+ * from irq context, so normal spinlocks can be used.
+ *
+ * A return value of false indicates the fence already passed,
+ * or some failure occurred that made it impossible to enable
+ * signaling. True indicates successful enabling.
+ *
+ * &dma_fence.error may be set in enable_signaling, but only when false
+ * is returned.
+ *
+ * Since many implementations can call dma_fence_signal() even when before
+ * @enable_signaling has been called there's a race window, where the
+ * dma_fence_signal() might result in the final fence reference being
+ * released and its memory freed. To avoid this, implementations of this
+ * callback should grab their own reference using dma_fence_get(), to be
+ * released when the fence is signalled (through e.g. the interrupt
+ * handler).
+ *
+ * This callback is mandatory.
+ */
bool (*enable_signaling)(struct dma_fence *fence);
+
+ /**
+ * @signaled:
+ *
+ * Peek whether the fence is signaled, as a fastpath optimization for
+ * e.g. dma_fence_wait() or dma_fence_add_callback(). Note that this
+ * callback does not need to make any guarantees beyond that a fence
+ * once indicates as signalled must always return true from this
+ * callback. This callback may return false even if the fence has
+ * completed already, in this case information hasn't propogated throug
+ * the system yet. See also dma_fence_is_signaled().
+ *
+ * May set &dma_fence.error if returning true.
+ *
+ * This callback is optional.
+ */
bool (*signaled)(struct dma_fence *fence);
+
+ /**
+ * @wait:
+ *
+ * Custom wait implementation, or dma_fence_default_wait.
+ *
+ * Must not be NULL, set to dma_fence_default_wait for default implementation.
+ * the dma_fence_default_wait implementation should work for any fence, as long
+ * as enable_signaling works correctly.
+ *
+ * Must return -ERESTARTSYS if the wait is intr = true and the wait was
+ * interrupted, and remaining jiffies if fence has signaled, or 0 if wait
+ * timed out. Can also return other error values on custom implementations,
+ * which should be treated as if the fence is signaled. For example a hardware
+ * lockup could be reported like that.
+ *
+ * This callback is mandatory.
+ */
signed long (*wait)(struct dma_fence *fence,
bool intr, signed long timeout);
+
+ /**
+ * @release:
+ *
+ * Called on destruction of fence to release additional resources.
+ * Can be called from irq context. This callback is optional. If it is
+ * NULL, then dma_fence_free() is instead called as the default
+ * implementation.
+ */
void (*release)(struct dma_fence *fence);
+ /**
+ * @fill_driver_data:
+ *
+ * Callback to fill in free-form debug info Returns amount of bytes
+ * filled, or negative error on failure.
+ *
+ * This callback is optional.
+ */
int (*fill_driver_data)(struct dma_fence *fence, void *data, int size);
+
+ /**
+ * @fence_value_str:
+ *
+ * Callback to fill in free-form debug info specific to this fence, like
+ * the sequence number.
+ *
+ * This callback is optional.
+ */
void (*fence_value_str)(struct dma_fence *fence, char *str, int size);
+
+ /**
+ * @timeline_value_str:
+ *
+ * Fills in the current value of the timeline as a string, like the
+ * sequence number. This should match what @fill_driver_data prints for
+ * the most recently signalled fence (assuming no delayed signalling).
+ */
void (*timeline_value_str)(struct dma_fence *fence,
char *str, int size);
};
@@ -189,7 +256,7 @@ void dma_fence_free(struct dma_fence *fence);
/**
* dma_fence_put - decreases refcount of the fence
- * @fence: [in] fence to reduce refcount of
+ * @fence: fence to reduce refcount of
*/
static inline void dma_fence_put(struct dma_fence *fence)
{
@@ -199,7 +266,7 @@ static inline void dma_fence_put(struct dma_fence *fence)
/**
* dma_fence_get - increases refcount of the fence
- * @fence: [in] fence to increase refcount of
+ * @fence: fence to increase refcount of
*
* Returns the same fence, with refcount increased by 1.
*/
@@ -213,7 +280,7 @@ static inline struct dma_fence *dma_fence_get(struct dma_fence *fence)
/**
* dma_fence_get_rcu - get a fence from a reservation_object_list with
* rcu read lock
- * @fence: [in] fence to increase refcount of
+ * @fence: fence to increase refcount of
*
* Function returns NULL if no refcount could be obtained, or the fence.
*/
@@ -227,7 +294,7 @@ static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
/**
* dma_fence_get_rcu_safe - acquire a reference to an RCU tracked fence
- * @fencep: [in] pointer to fence to increase refcount of
+ * @fencep: pointer to fence to increase refcount of
*
* Function returns NULL if no refcount could be obtained, or the fence.
* This function handles acquiring a reference to a fence that may be
@@ -289,14 +356,16 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence);
/**
* dma_fence_is_signaled_locked - Return an indication if the fence
* is signaled yet.
- * @fence: [in] the fence to check
+ * @fence: the fence to check
*
* Returns true if the fence was already signaled, false if not. Since this
* function doesn't enable signaling, it is not guaranteed to ever return
- * true if dma_fence_add_callback, dma_fence_wait or
- * dma_fence_enable_sw_signaling haven't been called before.
+ * true if dma_fence_add_callback(), dma_fence_wait() or
+ * dma_fence_enable_sw_signaling() haven't been called before.
*
- * This function requires fence->lock to be held.
+ * This function requires &dma_fence.lock to be held.
+ *
+ * See also dma_fence_is_signaled().
*/
static inline bool
dma_fence_is_signaled_locked(struct dma_fence *fence)
@@ -314,17 +383,19 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
/**
* dma_fence_is_signaled - Return an indication if the fence is signaled yet.
- * @fence: [in] the fence to check
+ * @fence: the fence to check
*
* Returns true if the fence was already signaled, false if not. Since this
* function doesn't enable signaling, it is not guaranteed to ever return
- * true if dma_fence_add_callback, dma_fence_wait or
- * dma_fence_enable_sw_signaling haven't been called before.
+ * true if dma_fence_add_callback(), dma_fence_wait() or
+ * dma_fence_enable_sw_signaling() haven't been called before.
*
* It's recommended for seqno fences to call dma_fence_signal when the
* operation is complete, it makes it possible to prevent issues from
* wraparound between time of issue and time of use by checking the return
* value of this function before calling hardware-specific wait instructions.
+ *
+ * See also dma_fence_is_signaled_locked().
*/
static inline bool
dma_fence_is_signaled(struct dma_fence *fence)
@@ -342,8 +413,8 @@ dma_fence_is_signaled(struct dma_fence *fence)
/**
* __dma_fence_is_later - return if f1 is chronologically later than f2
- * @f1: [in] the first fence's seqno
- * @f2: [in] the second fence's seqno from the same context
+ * @f1: the first fence's seqno
+ * @f2: the second fence's seqno from the same context
*
* Returns true if f1 is chronologically later than f2. Both fences must be
* from the same context, since a seqno is not common across contexts.
@@ -355,8 +426,8 @@ static inline bool __dma_fence_is_later(u32 f1, u32 f2)
/**
* dma_fence_is_later - return if f1 is chronologically later than f2
- * @f1: [in] the first fence from the same context
- * @f2: [in] the second fence from the same context
+ * @f1: the first fence from the same context
+ * @f2: the second fence from the same context
*
* Returns true if f1 is chronologically later than f2. Both fences must be
* from the same context, since a seqno is not re-used across contexts.
@@ -372,8 +443,8 @@ static inline bool dma_fence_is_later(struct dma_fence *f1,
/**
* dma_fence_later - return the chronologically later fence
- * @f1: [in] the first fence from the same context
- * @f2: [in] the second fence from the same context
+ * @f1: the first fence from the same context
+ * @f2: the second fence from the same context
*
* Returns NULL if both fences are signaled, otherwise the fence that would be
* signaled last. Both fences must be from the same context, since a seqno is
@@ -398,7 +469,7 @@ static inline struct dma_fence *dma_fence_later(struct dma_fence *f1,
/**
* dma_fence_get_status_locked - returns the status upon completion
- * @fence: [in] the dma_fence to query
+ * @fence: the dma_fence to query
*
* Drivers can supply an optional error status condition before they signal
* the fence (to indicate whether the fence was completed due to an error
@@ -422,8 +493,8 @@ int dma_fence_get_status(struct dma_fence *fence);
/**
* dma_fence_set_error - flag an error condition on the fence
- * @fence: [in] the dma_fence
- * @error: [in] the error to store
+ * @fence: the dma_fence
+ * @error: the error to store
*
* Drivers can supply an optional error status condition before they signal
* the fence, to indicate that the fence was completed due to an error
@@ -449,8 +520,8 @@ signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
/**
* dma_fence_wait - sleep until the fence gets signaled
- * @fence: [in] the fence to wait on
- * @intr: [in] if true, do an interruptible wait
+ * @fence: the fence to wait on
+ * @intr: if true, do an interruptible wait
*
* This function will return -ERESTARTSYS if interrupted by a signal,
* or 0 if the fence was signaled. Other error values may be
@@ -459,6 +530,8 @@ signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
* Performs a synchronous wait on this fence. It is assumed the caller
* directly or indirectly holds a reference to the fence, otherwise the
* fence might be freed before return, resulting in undefined behavior.
+ *
+ * See also dma_fence_wait_timeout() and dma_fence_wait_any_timeout().
*/
static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
{
--
2.17.0