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.brezil...@bootlin.com>
Reviewed-by: Liviu Dudau <liviu.du...@arm.com> > --- > 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) > + 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. > + * __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. > + * 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. > * @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 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯ _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel