Re: [PATCH] drm/i915: Fix broken mst get_hw_state.

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Wed, 2015-09-02 at 16:14 +0200, Maarten Lankhorst wrote:
> Op 02-09-15 om 16:07 schreef Ander Conselvan De Oliveira:
> > On Thu, 2015-08-27 at 13:13 +0200, Maarten Lankhorst wrote:
> > > connector->encoder is initialized as NULL. Fix this by setting it in
> > > during pre enable. MST connectors are not read out during initial hw
> > > readout, and have no fixed encoder mappings. So it's harmless to
> > > return false when the connector has never been assigned to an encoder.
> > >    
> > > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > > ---
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 738178a0ac96..e3922d973db0 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -6283,7 +6283,7 @@ static void intel_connector_check_state(struct intel_connector 
> > > *connector)
> > >  		      connector->base.name);
> > >  
> > >  	if (connector->get_hw_state(connector)) {
> > > -		struct drm_encoder *encoder = &connector->encoder->base;
> > > +		struct intel_encoder *encoder = connector->encoder;
> > >  		struct drm_connector_state *conn_state = connector->base.state;
> > >  
> > >  		I915_STATE_WARN(!crtc,
> > > @@ -6295,13 +6295,13 @@ static void intel_connector_check_state(struct intel_connector 
> > > *connector)
> > >  		I915_STATE_WARN(!crtc->state->active,
> > >  		      "connector is active, but attached crtc isn't\n");
> > >  
> > > -		if (!encoder)
> > > +		if (!encoder || encoder->type == INTEL_OUTPUT_DP_MST)
> > >  			return;
> > >  
> > > -		I915_STATE_WARN(conn_state->best_encoder != encoder,
> > > +		I915_STATE_WARN(conn_state->best_encoder != &encoder->base,
> > >  			"atomic encoder doesn't match attached encoder\n");
> > >  
> > > -		I915_STATE_WARN(conn_state->crtc != encoder->crtc,
> > > +		I915_STATE_WARN(conn_state->crtc != encoder->base.crtc,
> > >  			"attached encoder crtc differs from connector crtc\n");
> > >  	} else {
> > >  		I915_STATE_WARN(crtc && crtc->state->active,
> > > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > index ebf205462631..d606721b1788 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > @@ -159,6 +159,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder)
> > >  		return;
> > >  	}
> > >  
> > > +	/* MST encoders are bound to a crtc, not to a connector,
> > > +	 * force the mapping here for get_hw_state.
> > > +	 */
> > > +	found->encoder = encoder;
> > > +
> > >  	DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > >  	intel_mst->port = found->port;
> > >  
> > > @@ -392,7 +397,7 @@ static const struct drm_encoder_funcs intel_dp_mst_enc_funcs = {
> > >  
> > >  static bool intel_dp_mst_get_hw_state(struct intel_connector *connector)
> > >  {
> > > -	if (connector->encoder) {
> > > +	if (connector->encoder && connector->base.state->crtc) {
> > Is this here to cover the case where we disable this connector and assign the encoder to a 
> > different
> > connector? I guess this should work since if we disable the connector than crtc will be null, 
> > and
> > we'll assign a proper encoder when re-enabling. But now I'm wondering if it would make sense to 
> > set
> > connector->encoder back to NULL in post_disable.
> > 
> Yes, it's harmless to keep it non-null if conn_state->crtc is checked though. Saves another 
> pointless loop.

Fair enough.

Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
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