[PATCH 4/4] drm/i915/icl: Delay hotplug processing for tc ports

["José Roberto de Souza" <jose.souza@intel.com>]

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 | 76 ++++++++++++++++++++++++++++
 4 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 2a88a7eb871b..b81f8b55750e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2789,6 +2789,7 @@ 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 d978127e7208..2042711887f1 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5379,6 +5379,7 @@ 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)) {
@@ -5395,6 +5396,8 @@ 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);
@@ -6758,6 +6761,10 @@ 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 191c26e17f2d..06d282e4ecb7 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1137,7 +1137,11 @@ 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..d4094db1a3c3 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -323,6 +323,64 @@ static void i915_digport_work_func(struct work_struct *work)
 	}
 }
 
+#define TC_WA_DELAY_MSEC 150
+#define TC_WA_TRIES 5
+
+/*
+ * Test if TC dongle is responsive return true if so otherwise schedule a
+ * work to try again and return false
+ */
+static bool intel_hotplug_tc_wa_test(struct intel_dp *intel_dp)
+{
+	u8 buff;
+
+	intel_dp->tc_wa_count++;
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DPCD_REV, &buff, 1) != 1)
+		goto not_responsive;
+
+	if (!drm_probe_ddc(&intel_dp->aux.ddc))
+		goto not_responsive;
+
+	return true;
+
+not_responsive:
+	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");
+	}
+
+	return false;
+}
+
+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_connector *intel_connector = intel_dp->attached_connector;
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *intel_encoder = &intel_dig_port->base;
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct drm_device *dev = &dev_priv->drm;
+	bool ret;
+
+	if (!intel_digital_port_connected(intel_encoder))
+		return;
+
+	mutex_lock(&dev->mode_config.mutex);
+	ret = intel_hotplug_tc_wa_test(intel_dp);
+	if (ret)
+		ret = intel_encoder->hotplug(intel_encoder, intel_connector);
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (ret)
+		drm_kms_helper_hotplug_event(dev);
+}
+
 /*
  * Handle hotplug events outside the interrupt handler proper.
  */
@@ -358,9 +416,27 @@ static void i915_hotplug_work_func(struct work_struct *work)
 			continue;
 		intel_encoder = intel_connector->encoder;
 		if (hpd_event_bits & (1 << intel_encoder->hpd_pin)) {
+			struct intel_digital_port *dig_port = enc_to_dig_port(&intel_encoder->base);
+
 			DRM_DEBUG_KMS("Connector %s (pin %i) received hotplug event.\n",
 				      connector->name, intel_encoder->hpd_pin);
 
+			/*
+			 * TC WA: TC dongles can takes some time to be
+			 * responsible, so let's try to do a DPCD read to check
+			 * if it is ready, otherwise try again in a few msecs.
+			 */
+			if (IS_ICELAKE(dev_priv) &&
+			    intel_digital_port_connected(intel_encoder) &&
+			    dig_port->tc_type != TC_PORT_LEGACY) {
+				struct intel_dp *intel_dp;
+
+				intel_dp = enc_to_intel_dp(&intel_encoder->base);
+				intel_dp->tc_wa_count = 0;
+				if (!intel_hotplug_tc_wa_test(intel_dp))
+					continue;
+			}
+
 			changed |= intel_encoder->hotplug(intel_encoder,
 							  intel_connector);
 		}
-- 
2.19.1

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