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drm/i915: Check for downstream topology errors

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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
This commit is contained in:
Ramalingam C 2018-01-18 11:18:08 +05:30 committed by Sean Paul
parent 24b42cbadb
commit 49d85d0342
2 changed files with 8 additions and 0 deletions
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6
drivers/gpu/drm/i915/intel_hdcp.c
View file

@ -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) {

2
include/drm/drm_hdcp.h
View file

@ -20,6 +20,8 @@
#define DRM_HDCP_V_PRIME_PART_LEN 4
#define DRM_HDCP_V_PRIME_NUM_PARTS 5
#define DRM_HDCP_NUM_DOWNSTREAM(x) (x & 0x3f)
#define DRM_HDCP_MAX_CASCADE_EXCEEDED(x) (x & BIT(3))
#define DRM_HDCP_MAX_DEVICE_EXCEEDED(x) (x & BIT(7))
/* Slave address for the HDCP registers in the receiver */
#define DRM_HDCP_DDC_ADDR 0x3A