linux-kernel - Re: [PATCH] drm/atomic: Check new_crtc_state->active to determine if CRTC needs disable in self refresh mode

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Date:   Tue, 11 Jan 2022 10:47:29 -0500
From:   Alex Deucher <alexdeucher@...il.com>
To:     Liu Ying <victor.liu@....com>
Cc:     Maling list - DRI developers <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Rob Clark <robdclark@...omium.org>,
        David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>,
        NXP Linux Team <linux-imx@....com>,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH] drm/atomic: Check new_crtc_state->active to determine if
 CRTC needs disable in self refresh mode

Pushed out to drm-misc-next-fixes.

Alex

On Fri, Jan 7, 2022 at 9:07 PM Liu Ying <victor.liu@....com> wrote:
>
> On Fri, 2022-01-07 at 14:53 -0500, Alex Deucher wrote:
> > On Wed, Dec 29, 2021 at 11:07 PM Liu Ying <victor.liu@....com> wrote:
> > >
> > > Actual hardware state of CRTC is controlled by the member 'active'
> > > in
> > > struct drm_crtc_state instead of the member 'enable', according to
> > > the
> > > kernel doc of the member 'enable'.  In fact, the drm client modeset
> > > and atomic helpers are using the member 'active' to do the control.
> > >
> > > Referencing the member 'enable' of new_crtc_state, the function
> > > crtc_needs_disable() may fail to reflect if CRTC needs disable in
> > > self refresh mode, e.g., when the framebuffer emulation will be
> > > blanked
> > > through the client modeset helper with the next commit, the member
> > > 'enable' of new_crtc_state is still true while the member 'active'
> > > is
> > > false, hence the relevant potential encoder and bridges won't be
> > > disabled.
> > >
> > > So, let's check new_crtc_state->active to determine if CRTC needs
> > > disable
> > > in self refresh mode instead of new_crtc_state->enable.
> > >
> > > Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh
> > > mode in drivers")
> > > Cc: Sean Paul <seanpaul@...omium.org>
> > > Cc: Rob Clark <robdclark@...omium.org>
> > > Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
> > > Cc: Maxime Ripard <mripard@...nel.org>
> > > Cc: Thomas Zimmermann <tzimmermann@...e.de>
> > > Cc: David Airlie <airlied@...ux.ie>
> > > Cc: Daniel Vetter <daniel@...ll.ch>
> > > Signed-off-by: Liu Ying <victor.liu@....com>
> >
> > Reviewed-by: Alex Deucher <alexander.deucher@....com>
> >
> > Do you need someone to push this for you?
>
> Yes, please.  Thanks.
>
> Liu Ying
>
> >
> > Alex
> >
> > > ---
> > >  drivers/gpu/drm/drm_atomic_helper.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> > > b/drivers/gpu/drm/drm_atomic_helper.c
> > > index a7a05e1e26bb..9603193d2fa1 100644
> > > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > > @@ -1016,7 +1016,7 @@ crtc_needs_disable(struct drm_crtc_state
> > > *old_state,
> > >          * it's in self refresh mode and needs to be fully
> > > disabled.
> > >          */
> > >         return old_state->active ||
> > > -              (old_state->self_refresh_active && !new_state-
> > > >enable) ||
> > > +              (old_state->self_refresh_active && !new_state-
> > > >active) ||
> > >                new_state->self_refresh_active;
> > >  }
> > >
> > > --
> > > 2.25.1
> > >
>