[PATCH] drm/amd/display: Disallow enabling CRTC without primary plane with FB

[Michel Dänzer]

[ Dropping stable@ (fixes with Cc: stable are picked up for stable
branches once they land in Linus' tree, there's no point sending them to
stable@ during review), adding dri-devel ]

On 2018-04-18 10:26 PM, Harry Wentland wrote:
> The below commit
> 
>     "drm/atomic: Try to preserve the crtc enabled state in drm_atomic_remove_fb, v2"
> 
> introduces a slight behavioral change to rmfb. Instead of disabling a crtc
> when the primary plane is disabled, it now preserves it.
> 
> Since DC is currently not equipped to handle this we need to fail such
> a commit, otherwise we might see a corrupted screen.

How does the caller react to failing such a commit?


> This is based on Shirish's previous approach but avoids adding all
> planes to the new atomic state which leads to a full update in DC for
> any commit, and is not what we intend.
> 
> Theoretically DM should be able to deal with states with fully populated planes,
> even for simple updates, such as cursor updates. This should still be
> addressed in the future.
> 
> Signed-off-by: Harry Wentland <harry.wentland at amd.com>
> Cc: stable at vger.kernel.org
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 +++++++++-
>  1 file changed, 9 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 6f92a19bebd6..0bdc6b484bad 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4683,6 +4683,7 @@ static int dm_update_crtcs_state(struct amdgpu_display_manager *dm,
>  		struct amdgpu_dm_connector *aconnector = NULL;
>  		struct drm_connector_state *new_con_state = NULL;
>  		struct dm_connector_state *dm_conn_state = NULL;
> +		struct drm_plane_state *new_plane_state = NULL;
>  
>  		new_stream = NULL;
>  
> @@ -4690,6 +4691,13 @@ static int dm_update_crtcs_state(struct amdgpu_display_manager *dm,
>  		dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
>  		acrtc = to_amdgpu_crtc(crtc);
>  
> +		new_plane_state = drm_atomic_get_new_plane_state(state, new_crtc_state->crtc->primary);
> +
> +		if (new_crtc_state->enable && new_plane_state && !new_plane_state->fb) {
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +
>  		aconnector = amdgpu_dm_find_first_crtc_matching_connector(state, crtc);
>  
>  		/* TODO This hack should go away */
> @@ -4894,7 +4902,7 @@ static int dm_update_planes_state(struct dc *dc,
>  			if (!dm_old_crtc_state->stream)
>  				continue;
>  
> -			DRM_DEBUG_DRIVER("Disabling DRM plane: %d on DRM crtc %d\n",
> +			DRM_DEBUG_ATOMIC("Disabling DRM plane: %d on DRM crtc %d\n",
>  					plane->base.id, old_plane_crtc->base.id);
>  
>  			if (!dc_remove_plane_from_context(
> 


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer