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

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>