On Tue, 29 Oct 2024, "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@xxxxxxxxx> wrote:
>> -----Original Message-----
>> From: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>
>> Sent: Tuesday, October 29, 2024 2:23 PM
>> To: intel-xe@xxxxxxxxxxxxxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>; Kandpal,
>> Suraj <suraj.kandpal@xxxxxxxxx>
>> Subject: [PATCH] drm/i915/hdcp: Add the loop only for DP encoders
>>
>> Add the loop on the first read and write only for DP/DPMST encoders as this
>> issue is only observed here no need to burden other encoders with extra
>> retries.
>
> It would make the motivation of the patch clearer if we describe "this issue" here.
Ditto for "the loop".
>
>>
>> Fixes: 9d5a05f86d2f ("drm/i915/hdcp: Retry first read and writes to
>> downstream")
>> Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/display/intel_hdcp.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c
>> b/drivers/gpu/drm/i915/display/intel_hdcp.c
>> index ed6aa87403e2..fcfb5a9f303a 100644
>> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
>> @@ -1503,6 +1503,8 @@ static int hdcp2_deauthenticate_port(struct
>> intel_connector *connector) static int
>> hdcp2_authentication_key_exchange(struct intel_connector *connector) {
>> struct intel_display *display = to_intel_display(connector);
>> + struct intel_digital_port *dig_port =
>> + intel_attached_dig_port(connector);
>> struct intel_hdcp *hdcp = &connector->hdcp;
>> union {
>> struct hdcp2_ake_init ake_init;
>> @@ -1513,12 +1515,18 @@ static int
>> hdcp2_authentication_key_exchange(struct intel_connector *connector)
>> } msgs;
>> const struct intel_hdcp_shim *shim = hdcp->shim;
>> size_t size;
>> - int ret, i;
>> + int ret, i, max_retries;
>>
>> /* Init for seq_num */
>> hdcp->seq_num_v = 0;
>> hdcp->seq_num_m = 0;
>>
>> + if (intel_encoder_is_dp(&dig_port->base) ||
>> + intel_encoder_is_mst(&dig_port->base))
>> + max_retries = 10;
>> + else
>> + max_retries = 1;
>> +
>> ret = hdcp2_prepare_ake_init(connector, &msgs.ake_init);
>> if (ret < 0)
>> return ret;
>> @@ -1536,7 +1544,7 @@ static int
>> hdcp2_authentication_key_exchange(struct intel_connector *connector)
>> * authentication. The values of 10 and delay of 50ms was decided
>> based
>> * on multiple trial and errors.
>> */
>
> Perhaps this comment can use an update too.
>
> Functionally LGTM.
>
> Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
>
>> - for (i = 0; i < 10; i++) {
>> + for (i = 0; i < max_retries; i++) {
>> if (!intel_hdcp2_get_capability(connector)) {
>> msleep(50);
>> continue;
>> --
>> 2.34.1
>
--
Jani Nikula, Intel
