On Mon, Aug 17, 2020 at 11:03:42AM +0200, Gerd Hoffmann wrote:
> Hi,
>
> > > --- a/drivers/gpu/drm/virtio/virtgpu_display.c
> > > +++ b/drivers/gpu/drm/virtio/virtgpu_display.c
> > > @@ -100,6 +100,7 @@ static void virtio_gpu_crtc_atomic_enable(struct drm_crtc *crtc,
> > > struct virtio_gpu_output *output = drm_crtc_to_virtio_gpu_output(crtc);
> > >
> > > output->enabled = true;
> > > + output->need_update = true;
>
> > > --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
> > > +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
> > > @@ -163,7 +163,8 @@ static void virtio_gpu_primary_plane_update(struct drm_plane *plane,
> > > plane->state->src_w != old_state->src_w ||
> > > plane->state->src_h != old_state->src_h ||
> > > plane->state->src_x != old_state->src_x ||
> > > - plane->state->src_y != old_state->src_y) {
> > > + plane->state->src_y != old_state->src_y ||
> > > + output->need_update) {
> >
> > Uh instead of hand-rolling what's essentially a drm_crtc_needs_modeset
> > check, why not use that one? atomic helpers try to keep the usual suspects
> > for state transitions already handy, to avoid every driver rolling their
> > own. Or do I miss something here?
>
> Well, the virtio-gpu virtual hardware can't do plane updates and crtc
> updates independant from each other. So the crtc callbacks handle
> disable only (we don't need a fb for that) and leave the enable to the
> plane update.
>
> I suspect calling drm_atomic_crtc_needs_modeset() in plane update isn't
> going to fly ...
Digged a bit more, seems crtc_state->*_changed is cleared after modeset
so the following plane update wouldn't see it. Which I think means
there is no way around tracking that in need_update.
output->enabled is probably not needed though, seems I can replace that
by either output->crtc.state->enable or ->active. Not fully sure which
one, probably ->active.
take care,
Gerd
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