[PATCH v10 18/40] drm/i915: CP_IRQ handling for DP HDCP2.2 msgs

[Ramalingam C]

Implements the
	Waitqueue is created to wait for CP_IRQ
	Signaling the CP_IRQ arrival through atomic variable.
	For applicable DP HDCP2.2 msgs read wait for CP_IRQ.

As per HDCP2.2 spec "HDCP Transmitters must process CP_IRQ interrupts
when they are received from HDCP Receivers"

Without CP_IRQ processing, DP HDCP2.2 H_Prime msg was getting corrupted
while reading it based on corresponding status bit. This creates the
random failures in reading the DP HDCP2.2 msgs.

Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c   | 33 +++++++++++++++++++++++++--------
 drivers/gpu/drm/i915/intel_drv.h  |  7 +++++++
 drivers/gpu/drm/i915/intel_hdcp.c |  6 ++++++
 3 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index b13c41220ce0..4e36df266ab3 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5619,6 +5619,24 @@ void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
 		edp_panel_vdd_off_sync(intel_dp);
 }
 
+static void intel_dp_hdcp_wait_for_cp_irq(struct intel_hdcp *hdcp,
+					  int timeout)
+{
+	long ret;
+
+	/* Reinit */
+	atomic_set(&hdcp->cp_irq_recved, 0);
+
+#define C (atomic_read(&hdcp->cp_irq_recved) > 0)
+	ret = wait_event_interruptible_timeout(hdcp->cp_irq_queue, C,
+					       msecs_to_jiffies(timeout));
+
+	if (ret > 0)
+		atomic_set(&hdcp->cp_irq_recved, 0);
+	else if (!ret)
+		DRM_DEBUG_KMS("Timedout at waiting for CP_IRQ\n");
+}
+
 static
 int intel_dp_hdcp_write_an_aksv(struct intel_digital_port *intel_dig_port,
 				u8 *an)
@@ -5963,14 +5981,13 @@ intel_dp_hdcp2_wait_for_msg(struct intel_digital_port *intel_dig_port,
 		mdelay(timeout);
 		ret = 0;
 	} else {
-		/* TODO: In case if you need to wait on CP_IRQ, do it here */
-		ret = __wait_for(ret =
-				 hdcp2_detect_msg_availability(intel_dig_port,
-							       msg_id,
-							       &msg_ready),
-				 !ret && msg_ready, timeout * 1000,
-				 1000, 5 * 1000);
-
+		/*
+		 * Ignoring the return of the intel_dp_hdcp_wait_for_cp_irq,
+		 * Just to detect the msg availability before failing it.
+		 */
+		intel_dp_hdcp_wait_for_cp_irq(hdcp, timeout);
+		ret = hdcp2_detect_msg_availability(intel_dig_port,
+						    msg_id, &msg_ready);
 		if (!msg_ready)
 			ret = -ETIMEDOUT;
 	}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 747fe7361287..1901d12bacc4 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -464,6 +464,13 @@ struct intel_hdcp {
 	 * over re-Auth has to be triggered.
 	 */
 	u32 seq_num_m;
+
+	/*
+	 * Work queue to signal the CP_IRQ. Used for the waiters to read the
+	 * available information from HDCP DP sink.
+	 */
+	wait_queue_head_t cp_irq_queue;
+	atomic_t cp_irq_recved;
 };
 
 struct intel_connector {
diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
index 7ff29fb0aa2f..f38feeadb363 100644
--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -1805,6 +1805,9 @@ int intel_hdcp_init(struct intel_connector *connector,
 	if (hdcp2_supported)
 		intel_hdcp2_init(connector);
 
+	atomic_set(&hdcp->cp_irq_recved, 0);
+	init_waitqueue_head(&hdcp->cp_irq_queue);
+
 	return 0;
 }
 
@@ -1908,6 +1911,9 @@ void intel_hdcp_handle_cp_irq(struct intel_connector *connector)
 	if (!hdcp->shim)
 		return;
 
+	atomic_set(&connector->hdcp.cp_irq_recved, 1);
+	wake_up_all(&connector->hdcp.cp_irq_queue);
+
 	/*
 	 * CP_IRQ could be triggered due to 1. HDCP2.2 auth msgs availability,
 	 * 2. link failure and 3. repeater reauth request. At present we dont
-- 
2.7.4