Re: [PATCH v4 2/2] drm/i915: Enable hotplug retry

[Shane McKee <shane.mckee@intel.com>]

On Thu, Jul 11, 2019 at 12:49:35PM -0700, Nathan Ciobanu wrote:
> On Wed, Jul 10, 2019 at 03:15:00PM -0700, José Roberto de Souza wrote:
> > Right now we are aware of two cases that needs another hotplug retry:
> > - Unpowered type-c dongles
> > - HDMI slow unplug
> > 
> > Both have a complete explanation in the code to schedule another run
> > of the hotplug handler.
> > 
> > It could have more checks to just trigger the retry in those two
> > specific cases but why would sink signal a long pulse if there is
> > no change? Also the drawback of running the hotplug handler again
> > is really low and that could fix another cases that we are not
> > aware.
> > 
> > Also retrying for old DP ports(non-DDI) to make it consistent and not
> > cause CI failures if those systems are connected to chamelium boards
> > that will be used to simulate the issues reported in here.
> > 
> > v2: Also retrying for old DP ports(non-DDI)(Imre)
> > 
> > v4: Renamed INTEL_HOTPLUG_NOCHANGE to INTEL_HOTPLUG_UNCHANGED to keep
> > it consistent(Rodrigo)
> > 
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Imre Deak <imre.deak@intel.com>
> > Cc: Jani Nikula <jani.nikula@intel.com>
Tested-by: Shane McKee <shane.mckee@intel.com>
> > Reviewed-by: Imre Deak <imre.deak@intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_ddi.c  | 21 +++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_dp.c   |  7 ++++++
> >  drivers/gpu/drm/i915/display/intel_hdmi.c | 28 ++++++++++++++++++++++-
> >  3 files changed, 55 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index 734c004800f8..ea6d1873f6cb 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -4052,6 +4052,7 @@ intel_ddi_hotplug(struct intel_encoder *encoder,
> >  		  struct intel_connector *connector,
> >  		  bool irq_received)
> >  {
> > +	struct intel_digital_port *dig_port = enc_to_dig_port(&encoder->base);
> >  	struct drm_modeset_acquire_ctx ctx;
> >  	enum intel_hotplug_state state;
> >  	int ret;
> > @@ -4078,6 +4079,26 @@ intel_ddi_hotplug(struct intel_encoder *encoder,
> >  	drm_modeset_acquire_fini(&ctx);
> >  	WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
> >  
> > +	/*
> > +	 * Unpowered type-c dongles can take some time to boot and be
> > +	 * responsible, so here giving some time to those dongles to power up
> > +	 * and then retrying the probe.
> > +	 *
> > +	 * On many platforms the HDMI live state signal is known to be
> > +	 * unreliable, so we can't use it to detect if a sink is connected or
> > +	 * not. Instead we detect if it's connected based on whether we can
> > +	 * read the EDID or not. That in turn has a problem during disconnect,
> > +	 * since the HPD interrupt may be raised before the DDC lines get
> > +	 * disconnected (due to how the required length of DDC vs. HPD
> > +	 * connector pins are specified) and so we'll still be able to get a
> > +	 * valid EDID. To solve this schedule another detection cycle if this
> > +	 * time around we didn't detect any change in the sink's connection
> > +	 * status.
> > +	 */
> > +	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received &&
> > +	    !dig_port->dp.is_mst)
> > +		state = INTEL_HOTPLUG_RETRY;
> > +
> >  	return state;
> >  }
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 4423abbc7907..7106a2d80f79 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -4881,6 +4881,13 @@ intel_dp_hotplug(struct intel_encoder *encoder,
> >  	drm_modeset_acquire_fini(&ctx);
> >  	WARN(ret, "Acquiring modeset locks failed with %i\n", ret);
> >  
> > +	/*
> > +	 * Keeping it consistent with intel_ddi_hotplug() and
> > +	 * intel_hdmi_hotplug().
> > +	 */
> > +	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received)
> > +		state = INTEL_HOTPLUG_RETRY;
> > +
> >  	return state;
> >  }
> >  
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
> > index 0ebec69bbbfc..26c8556f6980 100644
> > --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> > @@ -3143,6 +3143,32 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
> >  		DRM_DEBUG_KMS("CEC notifier get failed\n");
> >  }
> >  
> > +static enum intel_hotplug_state
> > +intel_hdmi_hotplug(struct intel_encoder *encoder,
> > +		   struct intel_connector *connector, bool irq_received)
> > +{
> > +	enum intel_hotplug_state state;
> > +
> > +	state = intel_encoder_hotplug(encoder, connector, irq_received);
> > +
> > +	/*
> > +	 * On many platforms the HDMI live state signal is known to be
> > +	 * unreliable, so we can't use it to detect if a sink is connected or
> > +	 * not. Instead we detect if it's connected based on whether we can
> > +	 * read the EDID or not. That in turn has a problem during disconnect,
> > +	 * since the HPD interrupt may be raised before the DDC lines get
> > +	 * disconnected (due to how the required length of DDC vs. HPD
> > +	 * connector pins are specified) and so we'll still be able to get a
> > +	 * valid EDID. To solve this schedule another detection cycle if this
> > +	 * time around we didn't detect any change in the sink's connection
> > +	 * status.
> > +	 */
> > +	if (state == INTEL_HOTPLUG_UNCHANGED && irq_received)
> > +		state = INTEL_HOTPLUG_RETRY;
> > +
> > +	return state;
> > +}
> > +
> >  void intel_hdmi_init(struct drm_i915_private *dev_priv,
> >  		     i915_reg_t hdmi_reg, enum port port)
> >  {
> > @@ -3166,7 +3192,7 @@ void intel_hdmi_init(struct drm_i915_private *dev_priv,
> >  			 &intel_hdmi_enc_funcs, DRM_MODE_ENCODER_TMDS,
> >  			 "HDMI %c", port_name(port));
> >  
> > -	intel_encoder->hotplug = intel_encoder_hotplug;
> > +	intel_encoder->hotplug = intel_hdmi_hotplug;
> >  	intel_encoder->compute_config = intel_hdmi_compute_config;
> >  	if (HAS_PCH_SPLIT(dev_priv)) {
> >  		intel_encoder->disable = pch_disable_hdmi;
> > -- 
> > 2.22.0
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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