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 <ramalinga...@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

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