[PATCH] drm/i915/icl: Delay hotplug sequence for TC ports

* [PATCH] drm/i915/icl: Delay hotplug sequence for TC ports
@ 2019-01-23 18:51 José Roberto de Souza
  2019-01-23 18:57 ` ✗ Fi.CI.SPARSE: warning for " Patchwork
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: José Roberto de Souza @ 2019-01-23 18:51 UTC (permalink / raw)
  To: intel-gfx

Some unpowered 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 platforms because there was a hardware
bridge between DDI/DP ports and type-c controller adding a implicit
delay that hid this issue but ICL have type-c controllers integrated
to the SOC, causing sinks to not be detected.

So here it test if DP type-c port is responsive before proceed with
hotplug sequence, it try 5 times with a 150ms of delay between tries
before giving up.

If unpowered TBT dongles shows up in the market this approach should
be extended to TBT ports too.

Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |   1 +
 drivers/gpu/drm/i915/intel_ddi.c     |   4 +
 drivers/gpu/drm/i915/intel_drv.h     |   2 +
 drivers/gpu/drm/i915/intel_hotplug.c | 108 +++++++++++++++++++++++++++
 4 files changed, 115 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 03db011caa8e..3fd8c3fa6515 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2639,6 +2639,7 @@ 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_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index b0bb8dfc2ed5..2c149843cacf 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -4258,6 +4258,10 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
 			goto err;
 
 		intel_dig_port->hpd_pulse = intel_dp_hpd_pulse;
+
+		if (IS_ICELAKE(dev_priv) && intel_port_is_tc(dev_priv, port))
+			INIT_DELAYED_WORK(&intel_dig_port->tc_wa_work,
+					  intel_hotplug_tc_wa_work);
 	}
 
 	/* In theory we don't need the encoder->type check, but leave it just in
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 33b733d37706..fbb6f78ce733 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1242,6 +1242,8 @@ struct intel_digital_port {
 	enum intel_display_power_domain ddi_io_power_domain;
 	bool tc_legacy_port:1;
 	enum tc_port_type tc_type;
+	struct delayed_work tc_wa_work;
+	u8 tc_wa_count;
 
 	void (*write_infoframe)(struct intel_encoder *encoder,
 				const struct intel_crtc_state *crtc_state,
diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index e027d2b4abe5..9838b60e8f63 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -342,6 +342,74 @@ static void i915_digport_work_func(struct work_struct *work)
 	}
 }
 
+#define TC_WA_DELAY_MSEC 150
+#define TC_WA_TRIES 5
+
+/*
+ * Test if type-c 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_digital_port *dig_port)
+{
+	struct intel_dp *intel_dp = &dig_port->dp;
+	u8 buffer;
+
+	dig_port->tc_wa_count++;
+
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_DPCD_REV, &buffer, 1) != 1)
+		goto not_responsive;
+
+	if (!drm_probe_ddc(&intel_dp->aux.ddc))
+		goto not_responsive;
+
+	return true;
+
+not_responsive:
+	if (dig_port->tc_wa_count < TC_WA_TRIES) {
+		const unsigned long delay = msecs_to_jiffies(TC_WA_DELAY_MSEC);
+
+		schedule_delayed_work(&dig_port->tc_wa_work, delay);
+	} else {
+		DRM_DEBUG_KMS("TC port not responsive, giving up\n");
+	}
+
+	return false;
+}
+
+void intel_hotplug_tc_wa_work(struct work_struct *work)
+{
+	struct delayed_work *delayed_work = to_delayed_work(work);
+	struct intel_digital_port *dig_port = container_of(delayed_work,
+							   struct intel_digital_port,
+							   tc_wa_work);
+	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
+	struct intel_encoder *intel_encoder = &dig_port->base;
+	struct intel_dp *intel_dp = &dig_port->dp;
+	struct intel_connector *intel_connector = intel_dp->attached_connector;
+	struct drm_device *dev = &dev_priv->drm;
+	intel_wakeref_t wakeref;
+	bool ret;
+
+	wakeref = intel_runtime_pm_get(dev_priv);
+
+	if (!intel_digital_port_connected(intel_encoder) ||
+	    dig_port->tc_type != TC_PORT_TYPEC) {
+		intel_runtime_pm_put(dev_priv, wakeref);
+		return;
+	}
+
+	mutex_lock(&dev->mode_config.mutex);
+	ret = intel_hotplug_tc_wa_test(dig_port);
+	if (ret)
+		ret = intel_encoder->hotplug(intel_encoder, intel_connector);
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (ret)
+		drm_kms_helper_hotplug_event(dev);
+
+	intel_runtime_pm_put(dev_priv, wakeref);
+}
+
 /*
  * Handle hotplug events outside the interrupt handler proper.
  */
@@ -377,9 +445,37 @@ 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);
 
+			/*
+			 * Type-C dongles WA: Unpowered type-C dongles can take
+			 * some time to be responsible, so let's try to do a
+			 * DPCD read to check if it is ready, otherwise skip
+			 * the call to the hotplug callback and schedule a work
+			 * to try a DPCD read again after a few micro-seconds.
+			 */
+			if (IS_ICELAKE(dev_priv) &&
+			    intel_port_is_tc(dev_priv, intel_encoder->port)) {
+				intel_wakeref_t wakeref;
+				bool skip_hotplug = false;
+
+				wakeref = intel_runtime_pm_get(dev_priv);
+
+				if (intel_digital_port_connected(intel_encoder) &&
+				    dig_port->tc_type == TC_PORT_TYPEC) {
+					dig_port->tc_wa_count = 0;
+					skip_hotplug = !intel_hotplug_tc_wa_test(dig_port);
+				}
+
+				intel_runtime_pm_put(dev_priv, wakeref);
+
+				if (skip_hotplug)
+					continue;
+			}
+
 			changed |= intel_encoder->hotplug(intel_encoder,
 							  intel_connector);
 		}
@@ -644,6 +740,8 @@ void intel_hpd_init_work(struct drm_i915_private *dev_priv)
 
 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 {
+	struct intel_encoder *encoder;
+
 	spin_lock_irq(&dev_priv->irq_lock);
 
 	dev_priv->hotplug.long_port_mask = 0;
@@ -656,6 +754,16 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 	cancel_work_sync(&dev_priv->hotplug.hotplug_work);
 	cancel_work_sync(&dev_priv->hotplug.poll_init_work);
 	cancel_delayed_work_sync(&dev_priv->hotplug.reenable_work);
+
+	for_each_intel_encoder(&dev_priv->drm, encoder) {
+		struct intel_digital_port *dig_port;
+
+		dig_port = enc_to_dig_port(&encoder->base);
+		/* tc_wa_work is only initialized for TC with DP ports */
+		if (IS_ICELAKE(dev_priv) && dig_port && dig_port->hpd_pulse)
+			cancel_delayed_work_sync(&dig_port->tc_wa_work);
+	}
+
 }
 
 bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
-- 
2.20.1

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