On Mon, 2 Jul 2018 10:02:52 +0200 Daniel Vetter <daniel@xxxxxxxx> wrote: > On Fri, Jun 29, 2018 at 01:17:17PM +0200, Boris Brezillon wrote: > > In some cases CRTCs are active but are not able to generating events, at > > least not at every frame at it's expected to. > > This is typically the case when the CRTC is feeding a writeback connector > > that has no job queued. In this situation the CRTC is usually stopped > > until a new job is queued, and this can lead to timeouts when part of > > the pipeline is updated but no new jobs are queued to the active > > writeback connector. > > > > In order to solve that, we add a ->no_vblank flag to drm_crtc_state > > and ask the CRTC drivers to set it to true when they know they're not > > able to generate VBLANK events. The core drm_atomic_helper_fake_vblank() > > helper can then be used to fake VBLANKs at commit time. > > > > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx> > > --- > > drivers/gpu/drm/drm_atomic_helper.c | 40 +++++++++++++++++++++++++++++++++++++ > > include/drm/drm_atomic_helper.h | 1 + > > include/drm/drm_crtc.h | 15 ++++++++++++++ > > 3 files changed, 56 insertions(+) > > > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > > index 69063bcf2334..ca586993c2a2 100644 > > --- a/drivers/gpu/drm/drm_atomic_helper.c > > +++ b/drivers/gpu/drm/drm_atomic_helper.c > > @@ -2051,6 +2051,46 @@ void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *old_state) > > } > > EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies); > > > > +/** > > + * drm_atomic_helper_fake_vblank - fake VBLANK events if needed > > + * @old_state: atomic state object with old state structures > > + * > > + * This function walks all CRTCs and fake VBLANK events on those with > > + * &drm_crtc_state.no_vblank set to true and &drm_crtc_state.event != NULL. > > + * The primary use of this function is writeback connectors working in oneshot > > + * mode and faking VBLANK events. In this case they only fake the VBLANK event > > + * when a job is queued, and any change to the pipeline that does not touch the > > + * connector is leading to timeouts when calling > > + * drm_atomic_helper_wait_for_vblanks() or > > + * drm_atomic_helper_wait_for_flip_done(). > > + * > > + * This is part of the atomic helper support for nonblocking commits, see > > + * drm_atomic_helper_setup_commit() for an overview. > > + */ > > +void drm_atomic_helper_fake_vblank(struct drm_atomic_state *old_state) > > +{ > > + struct drm_crtc_state *old_crtc_state, *new_crtc_state; > > + struct drm_crtc *crtc; > > + int i; > > + > > + for_each_oldnew_crtc_in_state(old_state, crtc, old_crtc_state, > > + new_crtc_state, i) { > > + unsigned long flags; > > + > > + if (!new_crtc_state->no_vblank && !old_crtc_state->no_vblank) > > Uh, this essentially makes it impossible to reset no_vblank. I don't want ->no_vblank to be reset by the core. It's up to the CRTC driver to clear/set it when something changes in the pipeline. > For control > flow state bits we only check the new state for it (see e.g. the various > *_changed or plane_bits or whatever). I tried with !new_crtc_state->no_vblank only, but then it does not handle the case where the CRTC and connector are being disabled, and I end up with a timeout. > > > + continue; > > + > > + spin_lock_irqsave(&old_state->dev->event_lock, flags); > > + if (new_crtc_state->event) { > > + drm_crtc_send_vblank_event(crtc, > > + new_crtc_state->event); > > + new_crtc_state->event = NULL; > > + } > > + spin_unlock_irqrestore(&old_state->dev->event_lock, flags); > > + } > > +} > > +EXPORT_SYMBOL(drm_atomic_helper_fake_vblank); > > + > > /** > > * drm_atomic_helper_commit_hw_done - setup possible nonblocking commit > > * @old_state: atomic state object with old state structures > > diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h > > index 26aaba58d6ce..99e2a5297c69 100644 > > --- a/include/drm/drm_atomic_helper.h > > +++ b/include/drm/drm_atomic_helper.h > > @@ -100,6 +100,7 @@ int __must_check drm_atomic_helper_swap_state(struct drm_atomic_state *state, > > int drm_atomic_helper_setup_commit(struct drm_atomic_state *state, > > bool nonblock); > > void drm_atomic_helper_wait_for_dependencies(struct drm_atomic_state *state); > > +void drm_atomic_helper_fake_vblank(struct drm_atomic_state *state); > > void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *state); > > void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *state); > > > > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h > > index 23eddbccab10..7435dc66c08a 100644 > > --- a/include/drm/drm_crtc.h > > +++ b/include/drm/drm_crtc.h > > @@ -87,6 +87,20 @@ struct drm_plane_helper_funcs; > > * @zpos_changed: zpos values of planes on this crtc have been updated > > * @color_mgmt_changed: color management properties have changed (degamma or > > * gamma LUT or CSC matrix) > > + * @no_vblank: reflects the ability of a CRTC to send VBLANK events. This state > > + * usually depends on the pipeline configuration, and the main usuage is > > + * CRTCs feeding a writeback connector operating in oneshot mode. In this > > + * case the VBLANK event is only generated when a job is queued to the > > + * writeback connector, and we want the core to fake VBLANK events when > > + * this part of the pipeline hasn't changed but others had or when the > > + * CRTC and connectors are disabled. > > s/are disabled/are getting disabled/ > > You'll never get a request for an event when it's already off. That's true. > > > + * __drm_atomic_helper_crtc_duplicate_state() will the value from the > > + * current state, the CRTC driver is then responsible for updating this > > + * field when needed. > > Not parsing the above ... probably missing a "... will not reset ..." Exactly. Will add the missing words. > > > + * Note that, even when no_blank is set to true, the CRTC driver can still > > + * steal the &drm_crtc_state.event object and send the event on its own. > > + * That's usually what happens when a job is queued to the writeback > > + * connector. > > The last sentence is confusing imo. Just drop it? Yes, I know, but it's also important to state that the ->no_blank + event == NULL is a valid combination, and just means that the driver decided to generate the event (that happens when a new WB job is queued). > > Please use the inline comment style for struct members, and then also > polish the formatting a bit (e.g. paragraph breaks, which are only > possible with the inline style). I considered that, but the other fields were already documented in the single block above the struct, so I thought keeping things consistent was better. Should I just add this field doc inline and keep the other ones where they are, or should I add a patch moving all docs inline? > > With the nits addressed: > > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > * @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes > > * @connector_mask: bitmask of (1 << drm_connector_index(connector)) of attached connectors > > * @encoder_mask: bitmask of (1 << drm_encoder_index(encoder)) of attached encoders > > @@ -118,6 +132,7 @@ struct drm_crtc_state { > > bool connectors_changed : 1; > > bool zpos_changed : 1; > > bool color_mgmt_changed : 1; > > + bool no_vblank : 1; > > > > /* attached planes bitmask: > > * WARNING: transitional helpers do not maintain plane_mask so > > -- > > 2.14.1 > > > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel