Re: [PATCH 03/14] drm: clear plane damage during full modeset

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

On Thu, Sep 06, 2018 at 04:12:39PM +0200, Daniel Vetter wrote:
> On Thu, Sep 06, 2018 at 03:02:32PM +0300, Ville Syrjälä wrote:
> > On Wed, Sep 05, 2018 at 04:38:50PM -0700, Deepak Rawat wrote:
> > > Plane damage is irrelevant when full modeset happens so clear the damage
> > > blob property(If set by user-space). With damage blob cleared damage
> > > helper iterator will return full plane src as damage clip.
> > > 
> > > Signed-off-by: Deepak Rawat <drawat@vmware.com>
> > > ---
> > >  drivers/gpu/drm/drm_atomic_helper.c |  4 ++++
> > >  include/drm/drm_damage_helper.h     | 10 ++++++++++
> > >  2 files changed, 14 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > > index be83e2763c18..e06d2d5d582f 100644
> > > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > > @@ -31,6 +31,7 @@
> > >  #include <drm/drm_crtc_helper.h>
> > >  #include <drm/drm_atomic_helper.h>
> > >  #include <drm/drm_writeback.h>
> > > +#include <drm/drm_damage_helper.h>
> > >  #include <linux/dma-fence.h>
> > >  
> > >  #include "drm_crtc_helper_internal.h"
> > > @@ -88,6 +89,9 @@ drm_atomic_helper_plane_changed(struct drm_atomic_state *state,
> > >  			return;
> > >  
> > >  		crtc_state->planes_changed = true;
> > > +
> > > +		if (drm_atomic_crtc_needs_modeset(crtc_state))
> > > +			drm_plane_clear_damage(plane_state);
> > 
> > So if we sometimes magically clear it, where do we reinitialize it with
> > the user provided damage for the next update?
> > 
> > >  	}
> > >  }
> > >  
> > > diff --git a/include/drm/drm_damage_helper.h b/include/drm/drm_damage_helper.h
> > > index f1282b459a4f..1f988f7fdd72 100644
> > > --- a/include/drm/drm_damage_helper.h
> > > +++ b/include/drm/drm_damage_helper.h
> > > @@ -71,6 +71,16 @@ drm_plane_get_damage_clips(const struct drm_plane_state *state)
> > >  				   state->fb_damage_clips->data : NULL);
> > >  }
> > >  
> > > +/**
> > > + * drm_plane_clear_damage - clears damage blob in a plane state
> > > + * @state: Plane state
> > > + */
> > > +static inline void drm_plane_clear_damage(struct drm_plane_state *state)
> > > +{
> > > +	drm_property_blob_put(state->fb_damage_clips);
> > > +	state->fb_damage_clips = NULL;
> > 
> > Ah. So you're trying to clear out the user provided damage here. That
> > doesn't really seem like sane sematics to me. Either the user provided
> > damage should stick always instead of just sometimes, or it should 
> > always be cleared once the update is done (ie. could clear in
> > duplicate_state() in that case).
> 
> Read patch 2 more careful, we always reset damage when duplicating state.
> So it's one-shot (like fences).

Ah, thanks for pointing it out. Was actually in patch 1 :)

> 
> But you might also want to ignore damage (and do a full upload) in other
> cases, like a modeset, or when you move your plane between crtc. This
> function here is for that.
> 
> And yes this should be explained in the kerneldoc. And _clear_damage is
> not a great name for what it's meant to do, that's just what it does. I
> think in the past I've suggested _full_damage() or something like that.
> -Daniel
> 
> > 
> > > +}
> > > +
> > >  void drm_plane_enable_fb_damage_clips(struct drm_plane *plane);
> > >  int
> > >  drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
> > > -- 
> > > 2.17.1
> > > 
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > 
> > -- 
> > Ville Syrjälä
> > Intel
> > _______________________________________________
> > dri-devel mailing list
> > 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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