Re: [PATCH 1/2] drm/i915/hdcp: Add DP HDCP2.2 timeout to read entire msg

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Hi Anshuman,

Changes look good to me as per the Errata.

There are minor comments, inline:

On 1/27/2021 1:54 PM, Anshuman Gupta wrote:
As documented in HDCP 2.2 DP Errata spec transmitter should abort the
authentication protocol in case transmitter has not received the
entire {AKE_Send_Cert, AKE_Send_H_prime, AKE_Send_Paring_Info} msg
within {110,7,5} miliseconds.

Adding above msg timeout values and aborting the HDCP authentication
in case it timedout to read entire msg.

https://www.digital-cp.com/sites/default/files/HDCP%202_2_DisplayPort_Errata_v3_0.pdf

Cc: Ramalingam C <ramalingam.c@xxxxxxxxx>
Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
---
  drivers/gpu/drm/i915/display/intel_dp_hdcp.c | 56 +++++++++++++-------
  include/drm/drm_hdcp.h                       |  3 ++
  2 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
index f372e25edab4..f7cc5cbcabc6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
@@ -292,39 +292,42 @@ struct hdcp2_dp_msg_data {
  	u8 msg_id;
  	u32 offset;
  	bool msg_detectable;
+	bool msg_can_timedout;

Perhaps we can just check if msg_read_timedout is not 0 , instead of adding bool msg_can_timedout.


  	u32 timeout;
  	u32 timeout2; /* Added for non_paired situation */
+	/* Timeout to read entire msg */
+	u32 msg_read_timeout;
  };
static const struct hdcp2_dp_msg_data hdcp2_dp_msg_data[] = {
-	{ HDCP_2_2_AKE_INIT, DP_HDCP_2_2_AKE_INIT_OFFSET, false, 0, 0 },
+	{ HDCP_2_2_AKE_INIT, DP_HDCP_2_2_AKE_INIT_OFFSET, false, false, 0, 0, 0},
  	{ HDCP_2_2_AKE_SEND_CERT, DP_HDCP_2_2_AKE_SEND_CERT_OFFSET,
-	  false, HDCP_2_2_CERT_TIMEOUT_MS, 0 },
+	  false, true, HDCP_2_2_CERT_TIMEOUT_MS, 0, HDCP_2_2_DP_CERT_READ_TIMEOUT_MS},
  	{ HDCP_2_2_AKE_NO_STORED_KM, DP_HDCP_2_2_AKE_NO_STORED_KM_OFFSET,
-	  false, 0, 0 },
+	  false, false, 0, 0, 0 },
  	{ HDCP_2_2_AKE_STORED_KM, DP_HDCP_2_2_AKE_STORED_KM_OFFSET,
-	  false, 0, 0 },
+	  false, false, 0, 0, 0 },
  	{ HDCP_2_2_AKE_SEND_HPRIME, DP_HDCP_2_2_AKE_SEND_HPRIME_OFFSET,
-	  true, HDCP_2_2_HPRIME_PAIRED_TIMEOUT_MS,
-	  HDCP_2_2_HPRIME_NO_PAIRED_TIMEOUT_MS },
+	  true, true, HDCP_2_2_HPRIME_PAIRED_TIMEOUT_MS,
+	  HDCP_2_2_HPRIME_NO_PAIRED_TIMEOUT_MS, HDCP_2_2_DP_HPRIME_READ_TIMEOUT_MS},
  	{ HDCP_2_2_AKE_SEND_PAIRING_INFO,
-	  DP_HDCP_2_2_AKE_SEND_PAIRING_INFO_OFFSET, true,
-	  HDCP_2_2_PAIRING_TIMEOUT_MS, 0 },
-	{ HDCP_2_2_LC_INIT, DP_HDCP_2_2_LC_INIT_OFFSET, false, 0, 0 },
+	  DP_HDCP_2_2_AKE_SEND_PAIRING_INFO_OFFSET, true, true,
+	  HDCP_2_2_PAIRING_TIMEOUT_MS, 0, HDCP_2_2_DP_PAIRING_READ_TIMEOUT_MS },
+	{ HDCP_2_2_LC_INIT, DP_HDCP_2_2_LC_INIT_OFFSET, false, false, 0, 0, 0 },
  	{ HDCP_2_2_LC_SEND_LPRIME, DP_HDCP_2_2_LC_SEND_LPRIME_OFFSET,
-	  false, HDCP_2_2_DP_LPRIME_TIMEOUT_MS, 0 },
-	{ HDCP_2_2_SKE_SEND_EKS, DP_HDCP_2_2_SKE_SEND_EKS_OFFSET, false,
-	  0, 0 },
+	  false, false, HDCP_2_2_DP_LPRIME_TIMEOUT_MS, 0, 0 },
+	{ HDCP_2_2_SKE_SEND_EKS, DP_HDCP_2_2_SKE_SEND_EKS_OFFSET, false, false,
+	  0, 0, 0 },
  	{ HDCP_2_2_REP_SEND_RECVID_LIST,
-	  DP_HDCP_2_2_REP_SEND_RECVID_LIST_OFFSET, true,
-	  HDCP_2_2_RECVID_LIST_TIMEOUT_MS, 0 },
-	{ HDCP_2_2_REP_SEND_ACK, DP_HDCP_2_2_REP_SEND_ACK_OFFSET, false,
-	  0, 0 },
+	  DP_HDCP_2_2_REP_SEND_RECVID_LIST_OFFSET, true, false,
+	  HDCP_2_2_RECVID_LIST_TIMEOUT_MS, 0, 0 },
+	{ HDCP_2_2_REP_SEND_ACK, DP_HDCP_2_2_REP_SEND_ACK_OFFSET, false, false,
+	  0, 0, 0 },
  	{ HDCP_2_2_REP_STREAM_MANAGE,
-	  DP_HDCP_2_2_REP_STREAM_MANAGE_OFFSET, false,
-	  0, 0 },
+	  DP_HDCP_2_2_REP_STREAM_MANAGE_OFFSET, false, false,
+	  0, 0, 0},
  	{ HDCP_2_2_REP_STREAM_READY, DP_HDCP_2_2_REP_STREAM_READY_OFFSET,
-	  false, HDCP_2_2_STREAM_READY_TIMEOUT_MS, 0 },
+	  false, false, HDCP_2_2_STREAM_READY_TIMEOUT_MS, 0, 0 },
  /* local define to shovel this through the write_2_2 interface */
  #define HDCP_2_2_ERRATA_DP_STREAM_TYPE	50
  	{ HDCP_2_2_ERRATA_DP_STREAM_TYPE,
@@ -513,6 +516,8 @@ int intel_dp_hdcp2_read_msg(struct intel_digital_port *dig_port,
  	u8 *byte = buf;
  	ssize_t ret, bytes_to_recv, len;
  	const struct hdcp2_dp_msg_data *hdcp2_msg_data;
+	ktime_t msg_end;
+	bool msg_expired;
hdcp2_msg_data = get_hdcp2_dp_msg_data(msg_id);
  	if (!hdcp2_msg_data)
@@ -539,6 +544,11 @@ int intel_dp_hdcp2_read_msg(struct intel_digital_port *dig_port,
  		len = bytes_to_recv > DP_AUX_MAX_PAYLOAD_BYTES ?
  		      DP_AUX_MAX_PAYLOAD_BYTES : bytes_to_recv;
+ /* Entire msg read timeout since initiate of msg read */
+		if (bytes_to_recv == size - 1)


IMHO, we can add the check if msg_read_timeout > 0, so as to skip for messages that do not have timeout requirement.


+			msg_end = ktime_add_ms(ktime_get_raw(),
+					       hdcp2_msg_data->msg_read_timeout);
+
  		ret = drm_dp_dpcd_read(&dig_port->dp.aux, offset,
  				       (void *)byte, len);
  		if (ret < 0) {
@@ -551,6 +561,14 @@ int intel_dp_hdcp2_read_msg(struct intel_digital_port *dig_port,
  		byte += ret;
  		offset += ret;
  	}
+
+	msg_expired = ktime_after(ktime_get_raw(), msg_end);
+	if (msg_expired && hdcp2_msg_data->msg_can_timedout) {

As mentioned before, we can use msg_read_timeout here.


Regards,

Ankit

+		drm_dbg_kms(&i915->drm, "msg_id %d, entire msg read timeout(mSec): %d\n",
+			    msg_id, hdcp2_msg_data->msg_read_timeout);
+		return -ETIMEDOUT;
+	}
+
  	byte = buf;
  	*byte = msg_id;
diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h
index ac22c246542a..2b165a0f434f 100644
--- a/include/drm/drm_hdcp.h
+++ b/include/drm/drm_hdcp.h
@@ -224,9 +224,12 @@ struct hdcp2_rep_stream_ready {
/* HDCP2.2 TIMEOUTs in mSec */
  #define HDCP_2_2_CERT_TIMEOUT_MS		100
+#define HDCP_2_2_DP_CERT_READ_TIMEOUT_MS	110
  #define HDCP_2_2_HPRIME_NO_PAIRED_TIMEOUT_MS	1000
  #define HDCP_2_2_HPRIME_PAIRED_TIMEOUT_MS	200
+#define HDCP_2_2_DP_HPRIME_READ_TIMEOUT_MS	7
  #define HDCP_2_2_PAIRING_TIMEOUT_MS		200
+#define HDCP_2_2_DP_PAIRING_READ_TIMEOUT_MS	5
  #define	HDCP_2_2_HDMI_LPRIME_TIMEOUT_MS		20
  #define HDCP_2_2_DP_LPRIME_TIMEOUT_MS		7
  #define HDCP_2_2_RECVID_LIST_TIMEOUT_MS		3000
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