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

["Gupta, Anshuman" <anshuman.gupta@intel.com>]

Please also send this patch to dri-devel@lists.freedesktop.org as well because this is a drm change.

> -----Original Message-----
> From: Gupta, Anshuman
> Sent: Wednesday, January 27, 2021 12:55 PM
> To: Li, Juston <juston.li@intel.com>; intel-gfx@lists.freedesktop.org
> Cc: seanpaul@chromium.org; C, Ramalingam <ramalingam.c@intel.com>
> Subject: RE: [PATCH v2 3/4] drm/i915/hdcp: read RxInfo once when reading
> Send_Pairing_Info
> 
> 
> 
> > -----Original Message-----
> > From: Li, Juston <juston.li@intel.com>
> > Sent: Wednesday, January 27, 2021 12:21 PM
> > To: intel-gfx@lists.freedesktop.org
> > Cc: seanpaul@chromium.org; Gupta, Anshuman
> <anshuman.gupta@intel.com>;
> > C, Ramalingam <ramalingam.c@intel.com>; Li, Juston
> > <juston.li@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@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@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

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