Re: [PATCH AUTOSEL 5.4 13/15] drm/amdgpu/dc: Require primary plane to be enabled whenever the CRTC is

Michel Dänzer
2020-09-21T14:54:48Z

On 2020-09-21 4:40 p.m., Sasha Levin wrote:
> From: Michel Dänzer <mdaenzer@redhat.com>
>
> [ Upstream commit 2f228aab21bbc74e90e267a721215ec8be51daf7 ]
>
> Don't check drm_crtc_state::active for this either, per its
> documentation in include/drm/drm_crtc.h:
>
> * Hence drivers must not consult @active in their various
> * &drm_mode_config_funcs.atomic_check callback to reject an atomic
> * commit.
>
> atomic_remove_fb disables the CRTC as needed for disabling the primary
> plane.
>
> This prevents at least the following problems if the primary plane gets
> disabled (e.g. due to destroying the FB assigned to the primary plane,
> as happens e.g. with mutter in Wayland mode):
>
> * The legacy cursor ioctl returned EINVAL for a non-0 cursor FB ID
> (which enables the cursor plane).
> * If the cursor plane was enabled, changing the legacy DPMS property
> value from off to on returned EINVAL.
>
> v2:
> * Minor changes to code comment and commit log, per review feedback.
>
> GitLab: https://gitlab.gnome.org/GNOME/mutter/-/issues/1108
> GitLab: https://gitlab.gnome.org/GNOME/mutter/-/issues/1165
> GitLab: https://gitlab.gnome.org/GNOME/mutter/-/issues/1344
> Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
> Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

I'm a bit nervous about this getting backported so far back so quickly.
I'd prefer waiting for 5.9 final first at least.

--
Earthling Michel Dänzer | https://redhat.com
Libre software enthusiast | Mesa and X developer