On 2023-06-21 16:24, André Almeida wrote:
> From: Simon Ser <contact@xxxxxxxxxxx>
>
> 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@xxxxxxxxxxx>
> Reviewed-by: André Almeida <andrealmeid@xxxxxxxxxx>
> Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Harry
> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 ++++++++
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c | 12 ++++++++++++
> 2 files changed, 20 insertions(+)
>
> 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 514f6785a020..1d9b84e5835f 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -8136,7 +8136,15 @@ 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 440fc0869a34..30d4c6fd95f5 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
> @@ -398,6 +398,18 @@ 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;
