On Wed, 30 Oct 2024, "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@xxxxxxxxx> wrote:
>> -----Original Message-----
>> From: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>
>> Sent: Wednesday, October 30, 2024 8:23 AM
>> To: intel-xe@xxxxxxxxxxxxxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> Cc: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>; Borah, Chaitanya Kumar
>> <chaitanya.kumar.borah@xxxxxxxxx>
>> Subject: [PATCH] drm/i915/hdcp: Add the loop only for DP encoders
>>
>> Add the loop on the first read/write we do to give docks and dp encoders
>> some extra time to get their HDCP DPCD registers ready only for DP/DPMST
>> encoders as this issue is only observed here no need to burden other
>> encoders with extra retries as this causes the HDMI connector to have some
>> other timing issue and fails HDCP authentication.
>>
>> --v2
>> -Add intent of patch [Chaitanya]
>> -Add reasoning for loop [Jani]
>> -Make sure we forfiet the 50ms wait for non DP/DPMST encoders.
>>
>> Fixes: 9d5a05f86d2f ("drm/i915/hdcp: Retry first read and writes to
>> downstream")
>> Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
>> Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/display/intel_hdcp.c | 36 +++++++++++++++--------
>> 1 file changed, 23 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c
>> b/drivers/gpu/drm/i915/display/intel_hdcp.c
>> index ed6aa87403e2..c8ba69c51cce 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;
>> @@ -1513,31 +1515,39 @@ 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;
>> + bool is_dp_encoder;
>> + int ret, i, max_retries;
>>
>> /* Init for seq_num */
>> hdcp->seq_num_v = 0;
>> hdcp->seq_num_m = 0;
>>
>> + is_dp_encoder = intel_encoder_is_dp(&dig_port->base) ||
>> + intel_encoder_is_mst(&dig_port->base);
>> + if (is_dp_encoder)
>> + max_retries = 10;
>> + else
>> + max_retries = 1;
>> +
>> ret = hdcp2_prepare_ake_init(connector, &msgs.ake_init);
>> if (ret < 0)
>> return ret;
>>
>> /*
>> * Retry the first read and write to downstream at least 10 times
>> - * with a 50ms delay if not hdcp2 capable(dock decides to stop
>> advertising
>> - * hdcp2 capability for some reason). The reason being that
>> - * during suspend resume dock usually keeps the HDCP2 registers
>> inaccesible
>> - * causing AUX error. This wouldn't be a big problem if the userspace
>> - * just kept retrying with some delay while it continues to play low
>> - * value content but most userpace applications end up throwing an
>> error
>> - * when it receives one from KMD. This makes sure we give the dock
>> - * and the sink devices to complete its power cycle and then try HDCP
>> - * authentication. The values of 10 and delay of 50ms was decided
>> based
>> - * on multiple trial and errors.
>> + * with a 50ms delay if not hdcp2 capable for DP/DPMST encoders
>> + * (dock decides to stop advertising hdcp2 capability for some
>> reason).
>> + * The reason being that during suspend resume dock usually keeps
>> the
>> + * HDCP2 registers inaccesible causing AUX error. This wouldn't be a
>> + * big problem if the userspace just kept retrying with some delay
>> while
>> + * it continues to play low value content but most userpace
>> applications
>> + * end up throwing an error when it receives one from KMD. This
>> makes
>> + * sure we give the dock and the sink devices to complete its power
>> cycle
>> + * and then try HDCP authentication. The values of 10 and delay of
>> 50ms
>> + * was decided based on multiple trial and errors.
>> */
>> - for (i = 0; i < 10; i++) {
>> - if (!intel_hdcp2_get_capability(connector)) {
>> + for (i = 0; i < max_retries; i++) {
>> + if (!intel_hdcp2_get_capability(connector) &&
>> is_dp_encoder) {
>
> Now I am a bit confused, if you are using this Boolean here. Do you
> still need different values for max_retries?
Even more confusing, if you get false for hdcp2 cap with HDMI, you'll
continue with this stuff anyway?! What's the point in that?
BR,
Jani.
>
> Regards
>
> Chaitanya
>
>> msleep(50);
>> continue;
>> }
>> --
>> 2.34.1
>
--
Jani Nikula, Intel
