Re: [PATCH v8 12/12] drm/i915: Check TMDS clock DP to HDMI dongle

[Mika Kahola <mika.kahola@intel.com>]

On Thu, 2016-09-08 at 15:48 +0300, Ville Syrjälä wrote:
> On Wed, Aug 17, 2016 at 01:49:49PM +0300, Mika Kahola wrote:
> > 
> > Respect max TMDS clock frequency from DPCD for active
> > DP to HDMI adapters.
> > 
> > Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_drv.h  |  3 +++
> >  drivers/gpu/drm/i915/intel_hdmi.c | 27 +++++++++++++++++++++++++++
> >  2 files changed, 30 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > b/drivers/gpu/drm/i915/intel_drv.h
> > index 1c700b0..b7fd551 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -817,6 +817,9 @@ struct intel_hdmi {
> >  	i915_reg_t hdmi_reg;
> >  	int ddc_bus;
> >  	struct {
> > +		int max_tmds_clock;
> > +	} dp_to_hdmi;
> > +	struct {
> >  		enum drm_dp_dual_mode_type type;
> >  		int max_tmds_clock;
> >  	} dp_dual_mode;
> > diff --git a/drivers/gpu/drm/i915/intel_hdmi.c
> > b/drivers/gpu/drm/i915/intel_hdmi.c
> > index 4df9f38..1469d00 100644
> > --- a/drivers/gpu/drm/i915/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> > @@ -1204,6 +1204,9 @@ static int hdmi_port_clock_limit(struct
> > intel_hdmi *hdmi,
> >  	int max_tmds_clock =
> > intel_hdmi_source_max_tmds_clock(to_i915(dev));
> >  
> >  	if (respect_downstream_limits) {
> > +		if (hdmi->dp_to_hdmi.max_tmds_clock)
> > +			max_tmds_clock = min(max_tmds_clock,
> > +					     hdmi-
> > >dp_to_hdmi.max_tmds_clock);
> >  		if (hdmi->dp_dual_mode.max_tmds_clock)
> >  			max_tmds_clock = min(max_tmds_clock,
> >  					     hdmi-
> > >dp_dual_mode.max_tmds_clock);
> > @@ -1373,11 +1376,33 @@ intel_hdmi_unset_edid(struct drm_connector
> > *connector)
> >  	intel_hdmi->dp_dual_mode.type = DRM_DP_DUAL_MODE_NONE;
> >  	intel_hdmi->dp_dual_mode.max_tmds_clock = 0;
> >  
> > +	intel_hdmi->dp_to_hdmi.max_tmds_clock = 0;
> > +
> >  	kfree(to_intel_connector(connector)->detect_edid);
> >  	to_intel_connector(connector)->detect_edid = NULL;
> >  }
> >  
> >  static void
> > +intel_hdmi_dp_adapter_detect(struct drm_connector *connector)
> > +{
> > +	struct intel_hdmi *intel_hdmi =
> > intel_attached_hdmi(connector);
> > +	struct intel_digital_port *intel_dig_port =
> > +		hdmi_to_dig_port(intel_hdmi);
> > +	struct intel_dp *intel_dp = &intel_dig_port->dp;
> > +	int type = intel_dp->downstream_ports[0] &
> > DP_DS_PORT_TYPE_MASK;
> > +
> > +	if (type != DP_DS_PORT_TYPE_HDMI)
> > +		return;
> > +
> > +	intel_hdmi->dp_to_hdmi.max_tmds_clock =
> > +		drm_dp_downstream_max_clock(intel_dp->dpcd,
> > +					    intel_dp-
> > >downstream_ports);
> Poets driven by intel_hdmi don't have DPCD, so I don't know what this
> is supposed to achieve.
My understanding is that these HDMI adapters has DPCD and therefore I
placed this function. In addition, I think we should respect the clocks
if the adapter provides that information.

> 
> > 
> > +
> > +	DRM_DEBUG_KMS("DP HDMI adaptor detected (max TMDS clock :
> > %d kHz\n",
> > +		      intel_hdmi->dp_to_hdmi.max_tmds_clock);
> > +}
> > +
> > +static void
> >  intel_hdmi_dp_dual_mode_detect(struct drm_connector *connector,
> > bool has_edid)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(connector-
> > >dev);
> > @@ -1438,6 +1463,8 @@ intel_hdmi_set_edid(struct drm_connector
> > *connector, bool force)
> >  
> >  		intel_hdmi_dp_dual_mode_detect(connector, edid !=
> > NULL);
> >  
> > +		intel_hdmi_dp_adapter_detect(connector);
> > +
> >  		intel_display_power_put(dev_priv,
> > POWER_DOMAIN_GMBUS);
> >  	}
> >  
> > -- 
> > 1.9.1
-- 
Mika Kahola - Intel OTC

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