[PATCH] drm: Fix crtc color management when doing suspend/resume

[Alexandru-Cosmin Gheorghe]

Hi,

On Fri, Aug 24, 2018 at 09:51:03AM +0200, Maarten Lankhorst wrote:
> Op 23-08-18 om 17:11 schreef Alexandru Gheorghe:
> > When doing suspend/resume drivers usually use the
> > drm_atomic_helper_suspend/drm_atomic_helper_resume pair for saving the
> > state and then re-comitting it.
> >
> > The problems is that drm_crtc_state has a bool field called
> > color_mgmt_changed, which mali-dp and other drivers uses it to detect
> > if coefficients need to be reprogrammed, but that never happens
> > because the save state has color_mgmt_changed set to 0.
> >
> > Fix that by setting color_mgmt_changed to true if the crtc duplicated
> > state differs from the reset state.
> >
> > Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe at arm.com>
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 6dd5036545ec..e88aa62bc822 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -3196,8 +3196,13 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
> >  	for_each_new_plane_in_state(state, plane, new_plane_state, i)
> >  		state->planes[i].old_state = plane->state;
> >  
> > -	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i)
> > +	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
> >  		state->crtcs[i].old_state = crtc->state;
> > +		new_crtc_state->color_mgmt_changed =
> > +			new_crtc_state->degamma_lut != crtc->state->degamma_lut ||
> > +			new_crtc_state->ctm != crtc->state->ctm ||
> > +			new_crtc_state->gamma_lut != crtc->state->gamma_lut;
> Don't look at $obj->state please, use for_each_oldnew.
> 
> But it looks like we should set color_mgmt_changed in drm_atomic_helper_check_planes(),
> (or check_modeset if we want to know color_mgmt_changed from the planes atomic_check() too.
> The existing places that set color_mgmt_changed should be removed, because that check is now done in a single place. :)

drm_atomic_helper_check_modeset was the first candidate for me as
well, I think that makes more sense than
drm_atomic_helper_check_planes, don't you think ?

> >  	for_each_new_connector_in_state(state, connector, new_conn_state, i)
> >  		state->connectors[i].old_state = connector->state;
> 

-- 
Cheers,
Alex G