| Message ID | 1479773488-15048-1-git-send-email-gustavo@padovan.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Nov 22, 2016 at 09:11:28AM +0900, Gustavo Padovan wrote: > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk> > > Document IN_FENCE_FD and OUT_FENCE_PTR properties. > > v2: incorporate comments from Daniel Vetter > > Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> > --- > Documentation/gpu/drm-kms.rst | 6 +++++ > drivers/gpu/drm/drm_atomic.c | 52 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 58 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..f548e68 100644 > --- a/drivers/gpu/drm/drm_atomic.c > +++ b/drivers/gpu/drm/drm_atomic.c > @@ -1809,6 +1809,58 @@ 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 transfered 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. > + * > + * As a contrast, with implicit fencing the kernel keeps track of any > + * ongoing rendering, and automatically ensures that the atomic update waits > + * for any pending rendering to complete. For shared buffers represented with > + * a struct &dma_buf this is tracked in &reservation_object structures. > + * Implicit syncing is how Linux traditionally worked (e.g. DRI2/3 on X.org), > + * whereas explicit fencing is what Android wants. > + * > + * "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 cases and use a > + * fence_array if a merged fence is received. Passing -1 here means no > + * fences to wait on. > + * > + * If the Atomic Commit request has the DRM_MODE_ATOMIC_TEST_ONLY flag > + * it will only check if the Sync File is a valid one. > + * > + * On the driver side the fence is stored on the @fence parameter of > + * struct &drm_plane_state. Drivers which also support implicit fencing > + * should set the implicit fence using drm_atomic_set_fence_for_plane(), > + * to make sure there's consistent behaviour between drivers in precedence > + * of implicit vs. explicit fencing. > + * > + * "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. > + * > + * Note that out-fences don't have a special interface to drivers and are > + * internally represented by a struct &drm_pending_vblank_event in struct > + * &drm_crtc_state, which is also used by the async atomic commit helpers I've done an s/async/nonblocking/ here for consistency, since async commit == tearing commit (but it might still block), and applied the patch to drm-misc. Thanks a lot for typing this! -Daniel > + * and for the DRM event handling for existing userspace. > + */ > + > static struct dma_fence *get_crtc_fence(struct drm_crtc *crtc) > { > struct dma_fence *fence; > -- > 2.5.5 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
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..f548e68 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -1809,6 +1809,58 @@ 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 transfered 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. + * + * As a contrast, with implicit fencing the kernel keeps track of any + * ongoing rendering, and automatically ensures that the atomic update waits + * for any pending rendering to complete. For shared buffers represented with + * a struct &dma_buf this is tracked in &reservation_object structures. + * Implicit syncing is how Linux traditionally worked (e.g. DRI2/3 on X.org), + * whereas explicit fencing is what Android wants. + * + * "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 cases and use a + * fence_array if a merged fence is received. Passing -1 here means no + * fences to wait on. + * + * If the Atomic Commit request has the DRM_MODE_ATOMIC_TEST_ONLY flag + * it will only check if the Sync File is a valid one. + * + * On the driver side the fence is stored on the @fence parameter of + * struct &drm_plane_state. Drivers which also support implicit fencing + * should set the implicit fence using drm_atomic_set_fence_for_plane(), + * to make sure there's consistent behaviour between drivers in precedence + * of implicit vs. explicit fencing. + * + * "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. + * + * Note that out-fences don't have a special interface to drivers and are + * internally represented by a struct &drm_pending_vblank_event in struct + * &drm_crtc_state, which is also used by the async atomic commit helpers + * and for the DRM event handling for existing userspace. + */ + static struct dma_fence *get_crtc_fence(struct drm_crtc *crtc) { struct dma_fence *fence;