[Intel-gfx] [PATCH 2/2] drm/i915/mst: Use MST sideband message transaction for dpms

[Pandiyan, Dhinakaran]

On Tue, 2017-09-12 at 19:17 +0300, Ville Syrjälä wrote:
> On Tue, Sep 12, 2017 at 07:11:32PM +0300, Ville Syrjälä wrote:
> > On Tue, Sep 05, 2017 at 06:26:34PM -0700, Dhinakaran Pandiyan wrote:
> > > Use the POWER_DOWN_PHY and POWER_UP_PHY sideband message trasactions to
> > > set power states for downstream sinks. Apart from giving us the ability
> > > to set power state for individual sinks, this fixes the below test for
> > > me
> > > 
> > > $ xrandr --display :0 --output DP-2-2-8 --off
> > > $ xrandr --display :0 --output DP-2-2-1 --off
> > > $ xrandr --display :0 --output DP-2-2-8 --auto #Black screen
> > > $ xrandr --display :0 --output DP-2-2-1 --auto
> > > 
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Cc: Lyude <lyude at redhat.com>
> > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_ddi.c    | 6 ++++--
> > >  drivers/gpu/drm/i915/intel_dp_mst.c | 8 ++++----
> > >  2 files changed, 8 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > > index 1da3bb2cc4b4..8aebacc0aa31 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -2161,7 +2161,8 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
> > >  		intel_prepare_dp_ddi_buffers(encoder);
> > >  
> > >  	intel_ddi_init_dp_buf_reg(encoder);
> > > -	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > > +	if (!link_mst)
> > > +		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > >  	intel_dp_start_link_train(intel_dp);
> > >  	if (port != PORT_A || INTEL_GEN(dev_priv) >= 9)
> > >  		intel_dp_stop_link_train(intel_dp);
> > > @@ -2240,7 +2241,8 @@ static void intel_ddi_post_disable(struct intel_encoder *intel_encoder,
> > >  	if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
> > >  		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > >  
> > > -		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > > +		if (old_crtc_state && old_conn_state)
> > > +			intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > 
> > I would make that
> > !intel_crtc_has_type(DP_MST)
> > 
> > >  	}
> > >  
> > >  	val = I915_READ(DDI_BUF_CTL(port));
> > > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > index 8e3aad0ea60b..81e63724e24b 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > @@ -167,12 +167,11 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder,
> > >  	intel_dp->active_mst_links--;
> > >  
> > >  	intel_mst->connector = NULL;
> > > -	if (intel_dp->active_mst_links == 0) {
> > > +	if (intel_dp->active_mst_links == 0)
> > >  		intel_dig_port->base.post_disable(&intel_dig_port->base,
> > >  						  NULL, NULL);
> > > -
> > > -		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > > -	}
> > > +	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port,
> > > +				     false);
> > 
> > One thing that bothers me here is whether we'll start getting bogus link
> > training requests during shutdown since we'll do the D3 only after the
> > stream has been stopped. If you'll look at commit 7618138d8b40
> > ("drm/i915/ddi: Avoid long delays during system suspend / eDP
> > disabling") Imre explicitly moved the D3 earlier for SST to avoid this.
> > 

Interesting, that patch makes a lot of sense.

> > Hmm. Actually by the time we call mst_post_disable() we should have
> > deallocated the VC etc. so the current stream should be already
> > terminated at that point. So I think we should be able to do the
> > PHY_POWER_DOWN before we shut down the link, just like we do for SST.
> 
> Might also be nice to add comments near all the D3 calls to document
> that the order we use is there to prevent the sink from complaining
> about link loss when we shut down the link. Otherwise someone might
> get tempted to reorder things as a cleanup or something.
> 

Sure.

> > 
> > >  }
> > >  
> > >  static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
> > > @@ -197,6 +196,7 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder,
> > >  
> > >  	DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > >  
> > > +	drm_dp_send_power_updown_phy(&intel_dp->mst_mgr, connector->port, true);
> > >  	if (intel_dp->active_mst_links == 0)
> > >  		intel_dig_port->base.pre_enable(&intel_dig_port->base,
> > >  						pipe_config, NULL);
> > > -- 
> > > 2.11.0
> > 
> > -- 
> > Ville Syrjälä
> > Intel OTC
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