Re: [PATCH 1/3] drm/atomic: Use explicit old crtc state in drm_atomic_add_affected_planes()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Nov 05, 2018 at 10:26:01AM +0100, Daniel Vetter wrote:
> On Thu, Nov 01, 2018 at 08:46:44PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Replace 'crtc->state' with the explicit old crtc state.
> > 
> > Actually it shouldn't matter whether we use the old or the new
> > crtc state here since any plane that has been removed from the
> > crtc since the crtc state was duplicated will have been added
> > to the atomic state already. That is, you can't call
> > drm_atomic_set_crtc_for_plane() without having the new
> > plane state already in hand.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> I think this will break amdgpu_notify_freesync because that doesn't grab
> the crtc state first. Which worked with the old stuff, because adding a
> connector or plane will also add it's crtc. But with the new logic we'll
> just oops I think.

drm_atomic_add_affected_connectors() will add the crtc to the
state. So looks like it shouldn't oops.

> 
> Otoh, it's dead code, so what exactly are amd people doing again :-)

Heh. Thanks for the review.

> 
> Adding Harry so he's aware, but patch here looks good.
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/gpu/drm/drm_atomic.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 3dbfbddae7e6..064c48075917 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -927,6 +927,8 @@ int
> >  drm_atomic_add_affected_planes(struct drm_atomic_state *state,
> >  			       struct drm_crtc *crtc)
> >  {
> > +	const struct drm_crtc_state *old_crtc_state =
> > +		drm_atomic_get_old_crtc_state(state, crtc);
> >  	struct drm_plane *plane;
> >  
> >  	WARN_ON(!drm_atomic_get_new_crtc_state(state, crtc));
> > @@ -934,7 +936,7 @@ drm_atomic_add_affected_planes(struct drm_atomic_state *state,
> >  	DRM_DEBUG_ATOMIC("Adding all current planes for [CRTC:%d:%s] to %p\n",
> >  			 crtc->base.id, crtc->name, state);
> >  
> > -	drm_for_each_plane_mask(plane, state->dev, crtc->state->plane_mask) {
> > +	drm_for_each_plane_mask(plane, state->dev, old_crtc_state->plane_mask) {
> >  		struct drm_plane_state *plane_state =
> >  			drm_atomic_get_plane_state(state, plane);
> >  
> > -- 
> > 2.18.1
> > 
> > _______________________________________________
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> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel
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