On Mon, Aug 15, 2016 at 04:42:18PM +0100, Chris Wilson wrote:
Rendering operations to the dma-buf are tracked implicitly via the reservation_object (dmabuf->resv). This is used to allow poll() to wait upon outstanding rendering (or just query the current status of rendering). The dma-buf sync ioctl allows userspace to prepare the dma-buf for CPU access, which should include waiting upon rendering. (Some drivers may need to do more work to ensure that the dma-buf mmap is coherent as well as complete.)
v2: Always wait upon the reservation object implicitly. We choose to do it after the native handler in case it can do so more efficiently.
Testcase: igt/prime_vgem Testcase: igt/gem_concurrent_blit # *vgem* Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Eric Anholt eric@anholt.net Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-kernel@vger.kernel.org
drivers/dma-buf/dma-buf.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index ddaee60ae52a..cf04d249a6a4 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -586,6 +586,22 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); +static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
enum dma_data_direction direction)+{
- bool write = (direction == DMA_BIDIRECTIONAL ||
direction == DMA_TO_DEVICE);- struct reservation_object *resv = dmabuf->resv;
- long ret;
- /* Wait on any implicit rendering fences */
- ret = reservation_object_wait_timeout_rcu(resv, write, true,
MAX_SCHEDULE_TIMEOUT);- if (ret < 0)
return ret;- return 0;
+} /**
- dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
@@ -608,6 +624,13 @@ int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, if (dmabuf->ops->begin_cpu_access) ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
- /* Ensure that all fences are waited upon - but we first allow
* the native handler the chance to do so more efficiently if it* chooses. A double invocation here will be reasonably cheap no-op.*/- if (ret == 0)
ret = __dma_buf_begin_cpu_access(dmabuf, direction);
Not sure we should wait first and the flush or the other way round. But I don't think it'll matter for any current dma-buf exporter, so meh.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Sumits, can you pls pick this one up and put into drm-misc? -Daniel
- return ret;
} EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access); -- 2.8.1