From: Gustavo Padovan gustavo.padovan@collabora.co.uk
Document IN_FENCE_FD and OUT_FENCE_PTR properties.
Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.co.uk --- Documentation/gpu/drm-kms.rst | 6 ++++++ drivers/gpu/drm/drm_atomic.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+)
diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index 568f3c2..cdc9539 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -287,6 +287,12 @@ Tile Group Property .. kernel-doc:: drivers/gpu/drm/drm_connector.c :doc: Tile group
+Explicit Fencing Properties +--------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_atomic.c + :doc: explicit fencing properties + Existing KMS Properties -----------------------
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index b476ec5..7f33031 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -1809,6 +1809,37 @@ void drm_atomic_clean_old_fb(struct drm_device *dev, } EXPORT_SYMBOL(drm_atomic_clean_old_fb);
+/** + * DOC: explicit fencing properties + * + * Explicit fencing allows userspace to control the buffer synchronization + * between devices. A Fence or a group of fences are trasnfered to/from + * userspace using Sync File fds and there are two DRM properties for that. + * IN_FENCE_FD on each DRM Plane to send fences to the kernel and + * OUT_FENCE_PTR on each DRM CRTC to receive fences from the kernel. + * + * "IN_FENCE_FD”: + * Use this property to pass a fence that DRM should wait on before + * proceeding with the Atomic Commit request and show the framebuffer for + * the plane on the screen. The fence can be either a normal fence or a + * merged one, the sync_file framework will handle both case and use a + * fence_array if a merged fence is received. Passing -1 here means no + * fences to wait on. + * + * "OUT_FENCE_PTR”: + * Use this property to pass a file descriptor pointer to DRM. Once the + * Atomic Commit request call returns OUT_FENCE_PTR will be filled with + * the file descriptor number of a Sync File. This Sync File contains the + * CRTC fence that will be signaled when all framebuffers present on the + * Atomic Commit * request for that given CRTC are scanned out on the + * screen. + * + * The Atomic Commit request fails if a invalid pointer is passed. If the + * Atomic Commit request fails for any other reason the out fence fd + * returned will be -1. On a Atomic Commit with the + * DRM_MODE_ATOMIC_TEST_ONLY flag the out fence will also be set to -1. + */ + static struct dma_fence *get_crtc_fence(struct drm_crtc *crtc) { struct dma_fence *fence;