Re: [PATCH 12/17] drm: convert crtc to properties/state

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

On Mon, May 26, 2014 at 05:37:57PM +0200, Daniel Vetter wrote:
> On Mon, May 26, 2014 at 06:23:05PM +0300, Ville Syrjälä wrote:
> > On Mon, May 26, 2014 at 11:31:10AM +0200, Daniel Vetter wrote:
> > > On Sat, May 24, 2014 at 02:30:21PM -0400, Rob Clark wrote:
> > > > @@ -92,7 +100,18 @@ int drm_atomic_set_event(struct drm_device *dev,
> > > >  		struct drm_atomic_state *state, struct drm_mode_object *obj,
> > > >  		struct drm_pending_vblank_event *event)
> > > >  {
> > > > -	return -EINVAL;  /* for now */
> > > > +	switch (obj->type) {
> > > > +	case DRM_MODE_OBJECT_CRTC: {
> > > > +		struct drm_crtc_state *cstate =
> > > > +			drm_atomic_get_crtc_state(obj_to_crtc(obj), state);
> > > > +		if (IS_ERR(cstate))
> > > > +			return PTR_ERR(cstate);
> > > > +		cstate->event = event;
> > > > +		return 0;
> > > > +	}
> > > > +	default:
> > > > +		return -EINVAL;
> > > > +	}
> > > 
> > > Hm, I think if we only want completion events on crtcs (which I agree on)
> > 
> > I don't. Unless you have a nice way of passing some kind of "fbs now
> > available for rendering" list back to userland in the single crtc
> > event. Last time I looked making the drm event stuff deal with
> > variable length events looked more painful than just adding per
> > plane events. But I must admit that I didn't really try to do it.
> 
> Hm, why can't userspace keep a list of fb ids involved in a given crtc
> pageflip around and index those with the cookie we pass around?
> 
> I really don't see why the kernel has to implement a half-baked event
> multiplexer (which just copies the same thing n times), while userspace is
> perfectly capable of doing that itself?
> 
> Now if the timestamps would be genuinely different then I'd agree, but
> then that's not an atomic update.

User space can't do it if flips get issued faster than the vrefresh
rate. I still want my "moar fps" triple buffering mode.

-- 
Ville Syrjälä
Intel OTC