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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Message-ID: <d4ae974f38d96bc02db6c137e622315388a99ba0.camel@nxp.com>
Date:   Sat, 08 Jan 2022 10:07:10 +0800
From:   Liu Ying <victor.liu@....com>
To:     Alex Deucher <alexdeucher@...il.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

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
> >