[PATCH 04/20] drm/amd/display: Know what a pageflip is

[Grodzovsky, Andrey]

On 01/22/2019 01:28 PM, sunpeng.li at amd.com wrote:
> From: David Francis <David.Francis at amd.com>
>
> [Why]
> We were assuming that any commit with allow_modeset == false
> was a pageflip.  This was against drm intention and only
> worked by sheer luck
>
> [How]
> A pageflip is the change from one framebuffer to another

What about other references to state->allow_modeset in DM code ? You 
have one in  dm_determine_update_type_for_commit which will actually 
cause you to assume fast update because of state->allow_modeset == false.
Also - what about other types of plane updates which are more drastic 
(require full update) but will also have different FB, can't you wrongly 
assume they require page flip while it's actually needs 
commit_planes_to_stream ?

Andrey

>
> Signed-off-by: David Francis <David.Francis at amd.com>
> Reviewed-by: Harry Wentland <Harry.Wentland at amd.com>
> Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
> Acked-by: Leo Li <sunpeng.li at amd.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> 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 405c263..db060da 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4995,6 +4995,8 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
>   		struct drm_crtc *crtc = new_plane_state->crtc;
>   		struct drm_crtc_state *new_crtc_state;
>   		struct drm_framebuffer *fb = new_plane_state->fb;
> +		struct amdgpu_framebuffer *afb = to_amdgpu_framebuffer(fb);
> +		struct amdgpu_framebuffer *old_afb = to_amdgpu_framebuffer(old_plane_state->fb);
>   		bool pflip_needed;
>   		struct dm_plane_state *dm_new_plane_state = to_dm_plane_state(new_plane_state);
>   
> @@ -5010,7 +5012,8 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
>   		if (!new_crtc_state->active)
>   			continue;
>   
> -		pflip_needed = !state->allow_modeset;
> +		pflip_needed = old_plane_state->fb &&
> +			(old_plane_state->fb != new_plane_state->fb || afb->address != old_afb->address);
>   
>   		spin_lock_irqsave(&crtc->dev->event_lock, flags);
>   		if (acrtc_attach->pflip_status != AMDGPU_FLIP_NONE) {