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

["Nautiyal, Ankit K" <ankit.k.nautiyal@xxxxxxxxx>]

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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