Hi Daniel,
Two small comments:
On 03/21/2016 08:30 AM, Daniel Vetter wrote:
Just a bit of wording polish plus mentioning that it can fail and must be restarted.
Requested by Sumit.
Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Tiago Vignatti tiago.vignatti@intel.com Cc: Stéphane Marchesin marcheu@chromium.org Cc: David Herrmann dh.herrmann@gmail.com Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Daniel Vetter daniel.vetter@intel.com CC: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: intel-gfx@lists.freedesktop.org Cc: devel@driverdev.osuosl.org Signed-off-by: Daniel Vetter daniel.vetter@intel.com
Documentation/dma-buf-sharing.txt | 11 ++++++----- drivers/dma-buf/dma-buf.c | 2 +- 2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt index 32ac32e773e1..5c4e3e586ec8 100644 --- a/Documentation/dma-buf-sharing.txt +++ b/Documentation/dma-buf-sharing.txt @@ -352,7 +352,8 @@ Being able to mmap an export dma-buf buffer object has 2 main use-cases: No special interfaces, userspace simply calls mmap on the dma-buf fd, making sure that the cache synchronization ioctl (DMA_BUF_IOCTL_SYNC) is *always*
- used when the access happens. This is discussed next paragraphs.
- used when the access happens. Note that DMA_BUF_IOCTL_SYNC can fail with
- -EGAIN or -EINTR, in which case it must be restarted.
EGAIN -> EAGAIN
Some systems might need some sort of cache coherency management e.g. when CPU and GPU domains are being accessed through dma-buf at the same time. To @@ -366,10 +367,10 @@ Being able to mmap an export dma-buf buffer object has 2 main use-cases: want (with the new data being consumed by the GPU or say scanout device) - munmap once you don't need the buffer any more
- Therefore, for correctness and optimal performance, systems with the memory
- cache shared by the GPU and CPU i.e. the "coherent" and also the
- "incoherent" are always required to use SYNC_START and SYNC_END before and
- after, respectively, when accessing the mapped address.
- For correctness and optimal performance, it is always required to use
- SYNC_START and SYNC_END before and after, respectively, when accessing the
- mapped address. Userspace cannot on coherent access, even when there are
"Userspace cannot on coherent access"? Do you mean "cannot do"? Sorry, the meaning isn't clear to me.
Regards,
Hans
- systems where it just works without calling these ioctls.
2. Supporting existing mmap interfaces in importers diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 774a60f4309a..4a2c07ee6677 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -612,7 +612,7 @@ EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
- @dmabuf: [in] buffer to complete cpu access for.
- @direction: [in] length of range for cpu access.
- This call must always succeed.
*/
- Can return negative error values, returns 0 on success.
int dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)