[Intel-gfx] [PATCH v2 3/4] drm/i915/hdcp: read RxInfo once when reading Send_Pairing_Info

[Gupta, Anshuman]

> -----Original Message-----
> From: Li, Juston <juston.li at intel.com>
> Sent: Wednesday, January 27, 2021 12:21 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: seanpaul at chromium.org; Gupta, Anshuman
> <anshuman.gupta at intel.com>; C, Ramalingam <ramalingam.c at intel.com>;
> Li, Juston <juston.li at intel.com>
> Subject: [PATCH v2 3/4] drm/i915/hdcp: read RxInfo once when reading
> Send_Pairing_Info
> 
> Previously when reading Send_Pairing_Info, RxInfo by itself was read once
> to retrieve the DEVICE_COUNT and then a second time when reading the
> RepeaterAuth_Send_ReceiverID_List which contains RxInfo.
> 
> On a couple HDCP 2.2 docks, this second read attempt on RxInfo fails due to
> no Ack response. This behavior doesn't seem to be defined but regardless
> we can fix it by reading RxInfo once and storing it before reading the rest of
> RepeaterAuth_Send_ReceiverID_List once we know the size.
> 
> Modify get_receiver_id_list_size() to read and store RxInfo in the message
> buffer and also parse DEVICE_COUNT so we know the size of
> RepeaterAuth_Send_ReceiverID_List.
> 
> Afterwards, retrieve the rest of the message at the offset for seq_num_V.
> 
> Changes in v2:
> - remove unnecessary moving of drm_i915_private from patch 1
> 
> Signed-off-by: Juston Li <juston.li at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_hdcp.c | 29 ++++++++++----------
>  include/drm/drm_dp_helper.h                  |  2 +-
>  2 files changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
> b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
> index d1397af97f69..cd183944bc5a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
> @@ -475,11 +475,10 @@ int intel_dp_hdcp2_write_msg(struct
> intel_digital_port *dig_port,  }
> 
>  static
> -ssize_t get_receiver_id_list_size(struct intel_digital_port *dig_port)
> +ssize_t get_receiver_id_list_rx_info(struct intel_digital_port
> +*dig_port, u32 *dev_cnt, u8 *byte)
>  {
> -	u8 rx_info[HDCP_2_2_RXINFO_LEN];
> -	u32 dev_cnt;
>  	ssize_t ret;
> +	u8 *rx_info = byte;
> 
>  	ret = drm_dp_dpcd_read(&dig_port->dp.aux,
>  			       DP_HDCP_2_2_REG_RXINFO_OFFSET, @@ -
> 487,15 +486,11 @@ ssize_t get_receiver_id_list_size(struct
> intel_digital_port *dig_port)
>  	if (ret != HDCP_2_2_RXINFO_LEN)
>  		return ret >= 0 ? -EIO : ret;
> 
> -	dev_cnt = (HDCP_2_2_DEV_COUNT_HI(rx_info[0]) << 4 |
> +	*dev_cnt = (HDCP_2_2_DEV_COUNT_HI(rx_info[0]) << 4 |
>  		   HDCP_2_2_DEV_COUNT_LO(rx_info[1]));
> 
> -	if (dev_cnt > HDCP_2_2_MAX_DEVICE_COUNT)
> -		dev_cnt = HDCP_2_2_MAX_DEVICE_COUNT;
> -
> -	ret = sizeof(struct hdcp2_rep_send_receiverid_list) -
> -		HDCP_2_2_RECEIVER_IDS_MAX_LEN +
> -		(dev_cnt * HDCP_2_2_RECEIVER_ID_LEN);
> +	if (*dev_cnt > HDCP_2_2_MAX_DEVICE_COUNT)
> +		*dev_cnt = HDCP_2_2_MAX_DEVICE_COUNT;
> 
>  	return ret;
>  }
> @@ -511,6 +506,7 @@ 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;
> +	u32 dev_cnt;
> 
>  	hdcp2_msg_data = get_hdcp2_dp_msg_data(msg_id);
>  	if (!hdcp2_msg_data)
> @@ -523,17 +519,22 @@ int intel_dp_hdcp2_read_msg(struct
> intel_digital_port *dig_port,
> 
>  	hdcp->cp_irq_count_cached = atomic_read(&hdcp->cp_irq_count);
> 
> +	/* DP adaptation msgs has no msg_id */
> +	byte++;
> +
>  	if (msg_id == HDCP_2_2_REP_SEND_RECVID_LIST) {
> -		ret = get_receiver_id_list_size(dig_port);
> +		ret = get_receiver_id_list_rx_info(dig_port, &dev_cnt,
> byte);
>  		if (ret < 0)
>  			return ret;
> 
> -		size = ret;
> +		byte += ret;
> +		size = sizeof(struct hdcp2_rep_send_receiverid_list) -
> +		HDCP_2_2_RXINFO_LEN -
> HDCP_2_2_RECEIVER_IDS_MAX_LEN +
> +		(dev_cnt * HDCP_2_2_RECEIVER_ID_LEN);
>  	}
> -	bytes_to_recv = size - 1;
> 
>  	/* DP adaptation msgs has no msg_id */
Please remove this comment.
With that 
Acked-by: Anshuman Gupta <anshuman.gupta at intel.com>
> -	byte++;
> +	bytes_to_recv = size - 1;
> 
>  	while (bytes_to_recv) {
>  		len = bytes_to_recv > DP_AUX_MAX_PAYLOAD_BYTES ?
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index edffd1dcca3e..3b42392394ba 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1388,7 +1388,7 @@ enum drm_dp_phy {
>  #define DP_HDCP_2_2_LC_INIT_OFFSET
> 	DP_HDCP_2_2_REG_RN_OFFSET
>  #define DP_HDCP_2_2_LC_SEND_LPRIME_OFFSET
> 	DP_HDCP_2_2_REG_LPRIME_OFFSET
>  #define DP_HDCP_2_2_SKE_SEND_EKS_OFFSET
> 	DP_HDCP_2_2_REG_EDKEY_KS_OFFSET
> -#define DP_HDCP_2_2_REP_SEND_RECVID_LIST_OFFSET
> 	DP_HDCP_2_2_REG_RXINFO_OFFSET
> +#define DP_HDCP_2_2_REP_SEND_RECVID_LIST_OFFSET
> 	DP_HDCP_2_2_REG_SEQ_NUM_V_OFFSET
>  #define DP_HDCP_2_2_REP_SEND_ACK_OFFSET
> 	DP_HDCP_2_2_REG_V_OFFSET
>  #define DP_HDCP_2_2_REP_STREAM_MANAGE_OFFSET
> 	DP_HDCP_2_2_REG_SEQ_NUM_M_OFFSET
>  #define DP_HDCP_2_2_REP_STREAM_READY_OFFSET
> 	DP_HDCP_2_2_REG_MPRIME_OFFSET
> --
> 2.29.2