On 03/03/2017 08:37 AM, Laurent Pinchart wrote:
Hi Laura,
Thank you for the patch.
On Thursday 02 Mar 2017 13:44:36 Laura Abbott wrote:
Technically, calling dma_buf_map_attachment should return a buffer properly dma_mapped. Add calls to dma_map_sg to begin_cpu_access to ensure this happens. As a side effect, this lets Ion buffers take advantage of the dma_buf sync ioctls.
Signed-off-by: Laura Abbott labbott@redhat.com
drivers/staging/android/ion/ion.c | 101 +++++++++++++++++------------------ 1 file changed, 50 insertions(+), 51 deletions(-)
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index ce4adac..a931b30 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -795,10 +795,6 @@ void ion_client_destroy(struct ion_client *client) } EXPORT_SYMBOL(ion_client_destroy);
-static void ion_buffer_sync_for_device(struct ion_buffer *buffer,
struct device *dev,enum dma_data_direction direction);static struct sg_table *dup_sg_table(struct sg_table *table) { struct sg_table *new_table; @@ -825,22 +821,43 @@ static struct sg_table *dup_sg_table(struct sg_table *table) return new_table; }
+static void free_duped_table(struct sg_table *table) +{
- sg_free_table(table);
- kfree(table);
+}
static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction) { struct dma_buf *dmabuf = attachment->dmabuf; struct ion_buffer *buffer = dmabuf->priv;
- struct sg_table *table;
- int ret;
- /*
* TODO: Need to sync wrt CPU or device completely owning?*/- table = dup_sg_table(buffer->sg_table);
- ion_buffer_sync_for_device(buffer, attachment->dev, direction);
- return dup_sg_table(buffer->sg_table);
- if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
direction)){ret = -ENOMEM;goto err;- }
+err:
- free_duped_table(table);
- return ERR_PTR(ret);
}
static void ion_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table, enum dma_data_direction direction) {
- sg_free_table(table);
- kfree(table);
- dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
- free_duped_table(table);
}
void ion_pages_sync_for_device(struct device *dev, struct page *page, @@ -864,38 +881,6 @@ struct ion_vma_list { struct vm_area_struct *vma; };
-static void ion_buffer_sync_for_device(struct ion_buffer *buffer,
struct device *dev,enum dma_data_direction dir)-{
- struct ion_vma_list *vma_list;
- int pages = PAGE_ALIGN(buffer->size) / PAGE_SIZE;
- int i;
- pr_debug("%s: syncing for device %s\n", __func__,
dev ? dev_name(dev) : "null");- if (!ion_buffer_fault_user_mappings(buffer))
return;- mutex_lock(&buffer->lock);
- for (i = 0; i < pages; i++) {
struct page *page = buffer->pages[i];if (ion_buffer_page_is_dirty(page))ion_pages_sync_for_device(dev, ion_buffer_page(page),PAGE_SIZE, dir);ion_buffer_page_clean(buffer->pages + i);- }
- list_for_each_entry(vma_list, &buffer->vmas, list) {
struct vm_area_struct *vma = vma_list->vma;zap_page_range(vma, vma->vm_start, vma->vm_end - vma-vm_start);
- }
- mutex_unlock(&buffer->lock);
-}
static int ion_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct ion_buffer *buffer = vma->vm_private_data; @@ -1014,16 +999,24 @@ static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, struct ion_buffer *buffer = dmabuf->priv; void *vaddr;
- if (!buffer->heap->ops->map_kernel) {
pr_err("%s: map kernel is not implemented by this heap.\n",__func__);return -ENODEV;
- /*
* TODO: Move this elsewhere because we don't always need a vaddr*/- if (buffer->heap->ops->map_kernel) {
mutex_lock(&buffer->lock);vaddr = ion_buffer_kmap_get(buffer);mutex_unlock(&buffer->lock);
- mutex_lock(&buffer->lock);
- vaddr = ion_buffer_kmap_get(buffer);
- mutex_unlock(&buffer->lock);
- return PTR_ERR_OR_ZERO(vaddr);
- /*
* Close enough right now? Flag to skip sync?*/- if (!dma_map_sg(buffer->dev->dev.this_device, buffer->sg_table->sgl,
buffer->sg_table->nents,DMA_BIDIRECTIONAL))Aren't the dma_(un)map_* calls supposed to take a real, physical device as their first argument ? Beside, this doesn't seem to be the right place to create the mapping, as you mentioned in the commit message the buffer should be mapped in the dma_buf map handler. This is something that needs to be fixed, especially in the light of the comment in ion_buffer_create():
Yes, this might me a case of me getting the model incorrect again. dma_buf_{begin,end}_cpu_access do not take a device structure and from the comments:
/** * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific * preparations. Coherency is only guaranteed in the specified range for the * specified access direction. * @dmabuf: [in] buffer to prepare cpu access for. * @direction: [in] length of range for cpu access. * * Can return negative error values, returns 0 on success. */
If there are no buffer attachments, I guess the notion of 'coherency' doesn't apply here so there is no need to do any kind of syncing/mapping at all vs. trying to find a device out of nowhere.
I'll have to go back and re-think aligning sync/begin_cpu_access calls and dma_buf_map calls, or more likely not overthink this.
/* * this will set up dma addresses for the sglist -- it is not * technically correct as per the dma api -- a specific * device isn't really taking ownership here. However, in practice on * our systems the only dma_address space is physical addresses. * Additionally, we can't afford the overhead of invalidating every * allocation via dma_map_sg. The implicit contract here is that * memory coming from the heaps is ready for dma, ie if it has a * cached mapping that mapping has been invalidated */That's a showstopper in my opinion, the DMA address space can't be restricted to physical addresses, IOMMU have to be supported.
I missed a patch in this series to remove that. If Ion is going to exist outside of staging it should not be making that assumption at all so I want to drop it. Any performance implications should be fixed with the skip sync flag.
Thanks, Laura