drm/i915: Check for downstream topology errors
HDCP compliant Repeaters can support max of 127 devices and max
depth of 7 for downstream topology.
If these max limits are exceeded, repeater will set the
topology error flags MAX_CASCADE_EXCEEDED and/or MAX_DEVS_EXCEEDED
in Bstatus followed by asserting READY/CP_IRQ for HDCP transmitter.
This patch check for these error flags as soon as READY bit is asserted.
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
[seanpaul fixed checkpatch alignment issue]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1516254488-4971-5-git-send-email-ramalingam.c@intel.com
diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
index b50c03a..db95271 100644
--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -160,6 +160,12 @@ int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
if (ret)
return ret;
+ if (DRM_HDCP_MAX_DEVICE_EXCEEDED(bstatus[0]) ||
+ DRM_HDCP_MAX_CASCADE_EXCEEDED(bstatus[1])) {
+ DRM_ERROR("Max Topology Limit Exceeded\n");
+ return -EPERM;
+ }
+
/* If there are no downstream devices, we're all done. */
num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
if (num_downstream == 0) {