Re: [PATCH] drm/i915/hdcp: Disable the QSES check for HDCP 1.4 over MST

Anshuman, please review.

BR, Jani.

On Wed, 06 Jan 2021, Sean Paul sean@poorly.run wrote:

From: Sean Paul seanpaul@chromium.org

The HDCP 1.4 spec does not require the QUERY_STREAM_ENCRYPTION_STATUS check, it was always a nice-to-have. After deploying this across various devices, we've determined that some MST bridge chips do not properly support this call for HDCP 1.4 (namely Synaptics and Realtek).

I had considered creating a quirk for this, but I think it's more prudent to just disable the check entirely since I don't have an idea how widespread support is.

Signed-off-by: Sean Paul seanpaul@chromium.org

drivers/gpu/drm/i915/display/intel_dp_hdcp.c | 26 +------------------- 1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c index 03424d20e9f7..b6a9606bf09a 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c @@ -640,30 +640,6 @@ intel_dp_mst_hdcp_toggle_signalling(struct intel_digital_port *dig_port, return ret; }

-static -bool intel_dp_mst_hdcp_check_link(struct intel_digital_port *dig_port,

• 		  struct intel_connector *connector)
  

-{

• struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
• struct intel_dp *intel_dp = &dig_port->dp;
• struct drm_dp_query_stream_enc_status_ack_reply reply;
• int ret;
• if (!intel_dp_hdcp_check_link(dig_port, connector))

• return false;
  

• ret = drm_dp_send_query_stream_enc_status(&intel_dp->mst_mgr,

• 				  connector->port, &reply);
  

• if (ret) {

• drm_dbg_kms(&i915->drm,
  

• 	    "[CONNECTOR:%d:%s] failed QSES ret=%d\n",
  

• 	    connector->base.base.id, connector->base.name, ret);
  

• return false;
  

• }
• return reply.auth_completed && reply.encryption_enabled;

-}

static const struct intel_hdcp_shim intel_dp_mst_hdcp_shim = { .write_an_aksv = intel_dp_hdcp_write_an_aksv, .read_bksv = intel_dp_hdcp_read_bksv, @@ -674,7 +650,7 @@ static const struct intel_hdcp_shim intel_dp_mst_hdcp_shim = { .read_ksv_fifo = intel_dp_hdcp_read_ksv_fifo, .read_v_prime_part = intel_dp_hdcp_read_v_prime_part, .toggle_signalling = intel_dp_mst_hdcp_toggle_signalling,

• .check_link = intel_dp_mst_hdcp_check_link,

• .check_link = intel_dp_hdcp_check_link, .hdcp_capable = intel_dp_hdcp_capable,

  .protocol = HDCP_PROTOCOL_DP,