Re: [PATCH 5/6] drm/i915/icl: Delay hotplug processing for tc ports

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Oct 10, 2018 at 02:35:07PM -0700, José Roberto de Souza wrote:
> Some USB type-C dongles requires some time to power on before being
> able to process aux channel transactions.
> It was not a problem for older gens because there was a bridge
> between DP port and USB-C controller adding some delay but ICL
> handles type-C native.
> 
> So here trying to do a aux channel transaction at each 150ms for up 5
> times, before giving up.
> 
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h      |  1 +
>  drivers/gpu/drm/i915/intel_dp.c      |  7 ++++
>  drivers/gpu/drm/i915/intel_drv.h     |  6 ++-
>  drivers/gpu/drm/i915/intel_hotplug.c | 58 ++++++++++++++++++++++++++++
>  4 files changed, 71 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3017ef037fed..b3f1fc865366 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2810,6 +2810,7 @@ enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv,
>  				   enum port port);
>  bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
>  void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
> +void intel_hotplug_tc_wa_work(struct work_struct *__work);
>  
>  /* i915_irq.c */
>  static inline void i915_queue_hangcheck(struct drm_i915_private *dev_priv)
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 60e62a3c1e22..b945385cd5bc 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5289,6 +5289,7 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
>  {
>  	struct intel_digital_port *intel_dig_port = enc_to_dig_port(encoder);
>  	struct intel_dp *intel_dp = &intel_dig_port->dp;
> +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>  
>  	intel_dp_mst_encoder_cleanup(intel_dig_port);
>  	if (intel_dp_is_edp(intel_dp)) {
> @@ -5305,6 +5306,8 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
>  			unregister_reboot_notifier(&intel_dp->edp_notifier);
>  			intel_dp->edp_notifier.notifier_call = NULL;
>  		}
> +	} else if (IS_ICELAKE(dev_priv)) {
> +		cancel_delayed_work_sync(&intel_dp->tc_wa_work);
>  	}
>  
>  	intel_dp_aux_fini(intel_dp);
> @@ -6663,6 +6666,10 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>  		I915_WRITE(PEG_BAND_GAP_DATA, (temp & ~0xf) | 0xd);
>  	}
>  
> +	if (IS_ICELAKE(dev_priv) && !intel_dp_is_edp(intel_dp))
> +		INIT_DELAYED_WORK(&intel_dp->tc_wa_work,
> +				  intel_hotplug_tc_wa_work);
> +
>  	return true;
>  
>  fail:
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 3dea7a1bda7f..174a54aa966a 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1100,7 +1100,11 @@ struct intel_dp {
>  	int panel_power_cycle_delay;
>  	int backlight_on_delay;
>  	int backlight_off_delay;
> -	struct delayed_work panel_vdd_work;
> +	union {
> +		struct delayed_work panel_vdd_work;
> +		struct delayed_work tc_wa_work;
> +	};
> +	u8 tc_wa_count;
>  	bool want_panel_vdd;
>  	unsigned long last_power_on;
>  	unsigned long last_backlight_off;
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index 648a13c6043c..96546067f832 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -323,6 +323,45 @@ static void i915_digport_work_func(struct work_struct *work)
>  	}
>  }
>  
> +#define TC_WA_DELAY_MSEC 150
> +#define TC_WA_TRIES 5
> +
> +void intel_hotplug_tc_wa_work(struct work_struct *__work)
> +{
> +	struct intel_dp *intel_dp = container_of(to_delayed_work(__work),
> +						 struct intel_dp, tc_wa_work);
> +	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> +	struct intel_encoder *intel_encoder = &intel_dig_port->base;
> +	struct intel_connector *intel_connector = intel_dp->attached_connector;
> +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> +	struct drm_device *dev = &dev_priv->drm;
> +	u8 val;
> +
> +	if (!intel_port_is_tc(dev_priv, intel_encoder->port) ||
> +	    !intel_digital_port_connected(intel_encoder))
> +		return;
> +
> +	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DPCD_REV, &val, 1) < 1) {
> +		intel_dp->tc_wa_count++;
> +
> +		if (intel_dp->tc_wa_count < TC_WA_TRIES) {
> +			unsigned long delay;
> +
> +			delay = msecs_to_jiffies(TC_WA_DELAY_MSEC);
> +			schedule_delayed_work(&intel_dp->tc_wa_work, delay);
> +		} else {
> +			DRM_DEBUG_KMS("TC not responsive, giving up\n");
> +		}
> +	} else {
> +		mutex_lock(&dev->mode_config.mutex);
> +		val = intel_encoder->hotplug(intel_encoder, intel_connector);
> +		mutex_unlock(&dev->mode_config.mutex);
> +
> +		if (val)
> +			drm_kms_helper_hotplug_event(dev);
> +	}
> +}
> +
>  /*
>   * Handle hotplug events outside the interrupt handler proper.
>   */
> @@ -361,6 +400,25 @@ static void i915_hotplug_work_func(struct work_struct *work)
>  			DRM_DEBUG_KMS("Connector %s (pin %i) received hotplug event.\n",
>  				      connector->name, intel_encoder->hpd_pin);
>  
> +			/*
> +			 * TC WA: TC dongles takes some type to be
> +			 * responsible
> +			 */
> +			if (IS_ICELAKE(dev_priv) &&
> +			    intel_port_is_tc(dev_priv, intel_encoder->port) &&
> +			    intel_digital_port_connected(intel_encoder)) {
> +				struct intel_dp *intel_dp;
> +				unsigned long delay;
> +
> +				intel_dp = enc_to_intel_dp(&intel_encoder->base);
> +
> +				intel_dp->tc_wa_count = 0;
> +				delay = msecs_to_jiffies(TC_WA_DELAY_MSEC);
> +				schedule_delayed_work(&intel_dp->tc_wa_work,
> +						      delay);
> +				continue;
> +			}
> +
>  			changed |= intel_encoder->hotplug(intel_encoder,
>  							  intel_connector);

I think if we need such duct-tape we should just stuff it into the
.hotplug() hook.

>  		}
> -- 
> 2.19.1
> 
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-- 
Ville Syrjälä
Intel
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