> -----Original Message-----
> From: Kandpal, Suraj <suraj.kand...@intel.com>
> Sent: Wednesday, October 30, 2024 8:23 AM
> To: intel...@lists.freedesktop.org; intel-gfx@lists.freedesktop.org
> Cc: Kandpal, Suraj <suraj.kand...@intel.com>; Borah, Chaitanya Kumar
> <chaitanya.kumar.bo...@intel.com>
> 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.kand...@intel.com>
> Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.bo...@intel.com>
> ---
> 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?
Regards
Chaitanya
> msleep(50);
> continue;
> }
> --
> 2.34.1
