[Intel-gfx] [PATCH 26/29] drm/i915/dp_mst: Force modeset CRTC if DSC toggling requires it

[Imre Deak]

On Fri, Oct 27, 2023 at 05:20:10PM +0300, Ville Syrjälä wrote:
> On Tue, Oct 24, 2023 at 04:09:22AM +0300, Imre Deak wrote:
> > Enabling / disabling DSC decompression in the branch device downstream
> > of the source may reset the while branch device. To avoid this while the
> > streams are still active, force a modeset on all CRTC/ports connected to
> > this branch device.
> > 
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c |  4 ++
> >  drivers/gpu/drm/i915/display/intel_dp_mst.c  | 72 ++++++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_dp_mst.h  |  2 +
> >  3 files changed, 78 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 22f88389035bd..a33e5bbf5165a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -6490,6 +6490,10 @@ int intel_atomic_check(struct drm_device *dev,
> >  		if (!new_crtc_state->hw.enable || intel_crtc_needs_modeset(new_crtc_state))
> >  			continue;
> >  
> > +		if (intel_dp_mst_crtc_needs_modeset(state, crtc))
> > +			intel_modeset_pipes_in_mask_early(state, "MST topology",
> > +							  BIT(crtc->pipe));
> > +
> >  		if (intel_dp_mst_is_slave_trans(new_crtc_state)) {
> >  			enum transcoder master = new_crtc_state->mst_master_transcoder;
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index 9f4894c2e7860..d4dcfb2c09b2a 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -1606,3 +1606,75 @@ int intel_dp_mst_add_topology_state_for_crtc(struct intel_atomic_state *state,
> >  
> >  	return 0;
> >  }
> > +
> > +static struct intel_connector *
> > +get_connector_in_state_for_crtc(struct intel_atomic_state *state,
> > +				const struct intel_crtc *crtc)
> > +{
> > +	struct drm_connector_state *old_conn_state;
> > +	struct drm_connector_state *new_conn_state;
> > +	struct drm_connector *_connector;
> > +	int i;
> > +
> > +	for_each_oldnew_connector_in_state(&state->base, _connector,
> > +					   old_conn_state, new_conn_state, i) {
> > +		struct intel_connector *connector =
> > +			to_intel_connector(_connector);
> > +
> > +		if (old_conn_state->crtc == &crtc->base ||
> > +		    new_conn_state->crtc == &crtc->base)
> > +			return connector;
> > +	}
> > +
> > +	return NULL;
> > +}
> > +
> > +bool intel_dp_mst_crtc_needs_modeset(struct intel_atomic_state *state,
> > +				     struct intel_crtc *crtc)
> > +{
> > +	const struct intel_connector *crtc_connector;
> > +	const struct drm_connector_state *conn_state;
> > +	const struct drm_connector *_connector;
> > +	int i;
> > +
> > +	if (!intel_crtc_has_type(intel_atomic_get_new_crtc_state(state, crtc),
> > +				 INTEL_OUTPUT_DP_MST))
> > +		return false;
> > +
> > +	crtc_connector = get_connector_in_state_for_crtc(state, crtc);
> > +
> > +	if (!crtc_connector)
> > +		/* None of the connectors in the topology needs modeset */
> > +		return false;
> > +
> > +	for_each_new_connector_in_state(&state->base, _connector, conn_state, i) {
> > +		const struct intel_connector *connector =
> > +			to_intel_connector(_connector);
> > +		const struct intel_crtc_state *new_crtc_state =
> > +			intel_atomic_get_new_crtc_state(state, crtc);
> > +		const struct intel_crtc_state *old_crtc_state =
> > +			intel_atomic_get_old_crtc_state(state, crtc);
> 
> What's supposed to be happening here? You're just checking the same
> crtc every time through the loop.

Yes, it's borked, thanks for catching it. It's conn_state->crtc which
should be checked wrt. the change in the compression_enable state.

> > +
> > +		if (connector->mst_port != crtc_connector->mst_port)
> > +			continue;
> > +
> > +		if (!intel_crtc_needs_modeset(new_crtc_state))
> > +			continue;
> > +
> > +		if (old_crtc_state->dsc.compression_enable ==
> > +		    new_crtc_state->dsc.compression_enable)
> > +			continue;
> > +
> > +		/*
> > +		 * Toggling the compression flag because of this stream in the first
> > +		 * downstream branch device's UFP DPCD may reset the whole branch
> > +		 * device. To avoid the reset while other streams are also
> > +		 * active modeset the whole MST topology in this case.
> > +		 */
> > +		if (connector->dp.dsc_decompression_aux ==
> > +		    &connector->mst_port->aux)
> > +			return true;
> > +	}
> > +
> > +	return false;
> > +}
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.h b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> > index f1815bb722672..fc5e85776a858 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.h
> > @@ -22,5 +22,7 @@ bool intel_dp_mst_is_slave_trans(const struct intel_crtc_state *crtc_state);
> >  bool intel_dp_mst_source_support(struct intel_dp *intel_dp);
> >  int intel_dp_mst_add_topology_state_for_crtc(struct intel_atomic_state *state,
> >  					     struct intel_crtc *crtc);
> > +bool intel_dp_mst_crtc_needs_modeset(struct intel_atomic_state *state,
> > +				     struct intel_crtc *crtc);
> >  
> >  #endif /* __INTEL_DP_MST_H__ */
> > -- 
> > 2.39.2
> 
> -- 
> Ville Syrjälä
> Intel