drm/amd/display: only accept async flips for fast updates

commit 1ca67aba8d11c2849d395013e1fdce02918d5657 upstream.

Up until now, amdgpu was silently degrading to vsync when
user-space requested an async flip but the hardware didn't support
it.

The hardware doesn't support immediate flips when the update changes
the FB pitch, the DCC state, the rotation, enables or disables CRTCs
or planes, etc. This is reflected in the dm_crtc_state.update_type
field: UPDATE_TYPE_FAST means that immediate flip is supported.

Silently degrading async flips to vsync is not the expected behavior
from a uAPI point-of-view. Xorg expects async flips to fail if
unsupported, to be able to fall back to a blit. i915 already behaves
this way.

This patch aligns amdgpu with uAPI expectations and returns a failure
when an async flip is not possible.

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index b854eec2787e262b03c085ca4eac9718b72a4787..ee58caa3eafb8f3d2e90849789a688c86846d230 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -7757,7 +7757,15 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
                 * Only allow immediate flips for fast updates that don't
                 * change memory domain, FB pitch, DCC state, rotation or
                 * mirroring.
+                *
+                * dm_crtc_helper_atomic_check() only accepts async flips with
+                * fast updates.
                 */
+               if (crtc->state->async_flip &&
+                   acrtc_state->update_type != UPDATE_TYPE_FAST)
+                       drm_warn_once(state->dev,
+                                     "[PLANE:%d:%s] async flip with non-fast update\n",
+                                     plane->base.id, plane->name);
                bundle->flip_addrs[planes_count].flip_immediate =
                        crtc->state->async_flip &&
                        acrtc_state->update_type == UPDATE_TYPE_FAST &&

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
index 1ec643a0d00d20c62efb67986dd245868ea83909..b9b70f4562c727fe188a6739000725e8cbdd2e2c 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
@@ -406,6 +406,18 @@ static int dm_crtc_helper_atomic_check(struct drm_crtc *crtc,
                return -EINVAL;
        }
 
+       /*
+        * Only allow async flips for fast updates that don't change the FB
+        * pitch, the DCC state, rotation, etc.
+        */
+       if (crtc_state->async_flip &&
+           dm_crtc_state->update_type != UPDATE_TYPE_FAST) {
+               drm_dbg_atomic(crtc->dev,
+                              "[CRTC:%d:%s] async flips are only supported for fast updates\n",
+                              crtc->base.id, crtc->name);
+               return -EINVAL;
+       }
+
        /* In some use cases, like reset, no stream is attached */
        if (!dm_crtc_state->stream)
                return 0;