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.
v2: document new uAPI
v3: add comment about Intel hardware which needs one last
sync page-flip before being able to switch to async (Ville, Pekka)
Signed-off-by: Simon Ser <contact@xxxxxxxxxxx>
Co-developed-by: André Almeida <andrealmeid@xxxxxxxxxx>
Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
Reviewed-by: André Almeida <andrealmeid@xxxxxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Joshua Ashton <joshua@xxxxxxxxx>
Cc: Melissa Wen <mwen@xxxxxxxxxx>
Cc: Harry Wentland <hwentlan@xxxxxxx>
Cc: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_uapi.c | 28 +++++++++++++++++++++++++---
include/uapi/drm/drm_mode.h | 9 +++++++++
2 files changed, 34 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 79730fa1dd8e..ee24ed7e2edb 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -1278,6 +1278,18 @@ 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)
{
@@ -1318,9 +1330,16 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
}
if (arg->flags & DRM_MODE_PAGE_FLIP_ASYNC) {
- drm_dbg_atomic(dev,
- "commit failed: invalid flag DRM_MODE_PAGE_FLIP_ASYNC\n");
- return -EINVAL;
+ if (!dev->mode_config.async_page_flip) {
+ drm_dbg_atomic(dev,
+ "commit failed: DRM_MODE_PAGE_FLIP_ASYNC not supported\n");
+ return -EINVAL;
+ }
+ if (dev->mode_config.atomic_async_page_flip_not_supported) {
+ drm_dbg_atomic(dev,
+ "commit failed: DRM_MODE_PAGE_FLIP_ASYNC not supported with atomic\n");
+ return -EINVAL;
+ }
}
/* can't test and expect an event at the same time. */
@@ -1418,6 +1437,9 @@ 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) {
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 86a292c3185a..b39e78117b18 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -942,6 +942,15 @@ 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
--
2.37.3
