Re: [Intel-gfx] [PATCH v2] drm/i915: Do a better job at disabling primary plane in the noatomic case.

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 09 Dec 2015, Tomas M <tmezzadra@gmail.com> wrote:
> Hello,
>
> Is there any special reason this has not been merged yet?

No special reason. There's just the ordinary reason there is no review
on the patch yet.

BR,
Jani.



>
> Regards
>
> Tomas
>
> On Tue, Dec 1, 2015 at 6:07 AM, Jani Nikula <jani.nikula@linux.intel.com>
> wrote:
>
>> On Mon, 23 Nov 2015, Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> wrote:
>> > Op 13-11-15 om 14:28 schreef Ander Conselvan De Oliveira:
>> >> On Thu, 2015-11-12 at 14:58 +0100, Maarten Lankhorst wrote:
>> >>> Op 12-11-15 om 14:37 schreef Ander Conselvan De Oliveira:
>> >>>> On Wed, 2015-11-11 at 15:36 +0100, Maarten Lankhorst wrote:
>> >>>>> When disable_noatomic is called plane_mask is not reliable yet,
>> >>>>> and plane_state->visible = true even after disabling the primary
>> plane.
>> >>>> So the stale value of plane_state->visible causes a subsequent
>> modeset to
>> >>>> enable
>> >>>> the primary again?
>> >>> Probably not because it would get recalculated in calc_changes, but it
>> should
>> >>> really be set to false afterwards.
>> >> So basically I didn't understand how the wrong value of
>> plane_state->visible
>> >> causes the bug that was mentioned. I think a brief explanation in the
>> commit
>> >> message would be good.
>> > Well, apply with git am --scissors. Same patch but mentioning this.
>> >
>> > Is this better?
>>
>> Ander, ping?
>>
>> BR,
>> Jani.
>>
>> > ---->8-----
>> >
>> > When disable_noatomic is called plane_mask is not correct yet,
>> > and plane_state->visible = true is left as true after disabling
>> > the primary plane.
>> >
>> > Other planes are already disabled as part of crtc sanitization, only the
>> > primary is left active. But the plane_mask is not updated here. It gets
>> updated
>> > during fb takeover in modeset_gem_init, or set to the new value on
>> resume.
>> >
>> > This means that to disable the primary plane 1 <<
>> drm_plane_index(primary)
>> > needs to be used.
>> >
>> > Afterwards because the crtc is no longer active it's forbidden to keep
>> > plane_state->visible set, or a WARN_ON in intel_plane_atomic_calc_changes
>> > triggers. There are other code points that rely on accurate
>> plane_state->visible
>> > too, so make sure the bool is cleared.
>> >
>> >
>> > The other planes are already disabled in intel_sanitize_crtc, so
>> > they don't have to be handled here.
>> >
>> > Cc: stable@vger.kernel.org #v4.3, v4.2?
>> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92655
>> > Tested-by: Tomas Mezzadra <tmezzadra@gmail.com>
>> > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/intel_display.c | 4 +++-
>> >  1 file changed, 3 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_display.c
>> b/drivers/gpu/drm/i915/intel_display.c
>> > index b5f7493213b7..bc3282ab5ed2 100644
>> > --- a/drivers/gpu/drm/i915/intel_display.c
>> > +++ b/drivers/gpu/drm/i915/intel_display.c
>> > @@ -6267,9 +6267,11 @@ static void intel_crtc_disable_noatomic(struct
>> drm_crtc *crtc)
>> >               WARN_ON(intel_crtc->unpin_work);
>> >
>> >               intel_pre_disable_primary(crtc);
>> > +
>> > +             intel_crtc_disable_planes(crtc, 1 <<
>> drm_plane_index(crtc->primary));
>> > +             to_intel_plane_state(crtc->primary->state)->visible =
>> false;
>> >       }
>> >
>> > -     intel_crtc_disable_planes(crtc, crtc->state->plane_mask);
>> >       dev_priv->display.crtc_disable(crtc);
>> >       intel_crtc->active = false;
>> >       intel_update_watermarks(crtc);
>> > -- 2.1.0
>> >
>> > _______________________________________________
>> > Intel-gfx mailing list
>> > Intel-gfx@lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>> --
>> Jani Nikula, Intel Open Source Technology Center
>>

-- 
Jani Nikula, Intel Open Source Technology Center