Commit 4b4af74a authored by Simon Ser's avatar Simon Ser
Browse files

drm: allow DRM_MODE_PAGE_FLIP_ASYNC for atomic commits 



If the driver supports it, allow user-space to supply the
DRM_MODE_PAGE_FLIP_ASYNC flag to request an async page-flip.
Set drm_crtc_state.async_flip accordingly.

Document that drivers will reject atomic commits if an async
flip isn't possible. This allows user-space to fall back to
something else. For instance, Xorg falls back to a blit.
Another option is to wait as close to the next vblank as
possible before performing the page-flip to reduce latency.

Signed-off-by: default avatarSimon Ser <contact@emersion.fr>
Reviewed-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Co-developed-by: default avatarAndré Almeida <andrealmeid@igalia.com>
Signed-off-by: default avatarAndré Almeida <andrealmeid@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231122161941.320564-3-andrealmeid@igalia.com
parent 0e26cc72

drivers/gpu/drm/drm_atomic_uapi.c

+22 −3
Original line number Diff line number Diff line
@@ -1368,6 +1368,18 @@ static void complete_signaling(struct drm_device *dev, 
	kfree(fence_state);

}



static void

set_async_flip(struct drm_atomic_state *state)

{

	struct drm_crtc *crtc;

	struct drm_crtc_state *crtc_state;

	int i;



	for_each_new_crtc_in_state(state, crtc, crtc_state, i) {

		crtc_state->async_flip = true;

	}

}



int drm_mode_atomic_ioctl(struct drm_device *dev,

			  void *data, struct drm_file *file_priv)

{
@@ -1409,11 +1421,15 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, 
	}



	if (arg->flags & DRM_MODE_PAGE_FLIP_ASYNC) {

		if (!dev->mode_config.async_page_flip) {

			drm_dbg_atomic(dev,

			       "commit failed: invalid flag DRM_MODE_PAGE_FLIP_ASYNC\n");

				       "commit failed: DRM_MODE_PAGE_FLIP_ASYNC not supported\n");

			return -EINVAL;

		}



		async_flip = true;

	}



	/* can't test and expect an event at the same time. */

	if ((arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) &&

			(arg->flags & DRM_MODE_PAGE_FLIP_EVENT)) {
@@ -1514,6 +1530,9 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, 
	if (ret)

		goto out;



	if (arg->flags & DRM_MODE_PAGE_FLIP_ASYNC)

		set_async_flip(state);



	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {

		ret = drm_atomic_check_only(state);

	} else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {

include/uapi/drm/drm_mode.h

+9 −0
Original line number Diff line number Diff line
@@ -957,6 +957,15 @@ struct hdr_output_metadata { 
 * Request that the page-flip is performed as soon as possible, ie. with no

 * delay due to waiting for vblank. This may cause tearing to be visible on

 * the screen.

 *

 * When used with atomic uAPI, the driver will return an error if the hardware

 * doesn't support performing an asynchronous page-flip for this update.

 * User-space should handle this, e.g. by falling back to a regular page-flip.

 *

 * Note, some hardware might need to perform one last synchronous page-flip

 * before being able to switch to asynchronous page-flips. As an exception,

 * the driver will return success even though that first page-flip is not

 * asynchronous.

 */

#define DRM_MODE_PAGE_FLIP_ASYNC 0x02

#define DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE 0x4