drm/i915: Read Vprime thrice incase of mismatch

In case of V prime mismatch, DP HDCP spec mandates the re-read of
Vprime atleast twice.

This patch needed for DP HDCP1.4 CTS Test: 1B-05.

v2:
  Moved the V' validation into a function for retry. [Sean Paul]
v3:
  Removed Inline keyword and DRM_DEBUG_KMS are used [Sean Paul]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1522663834-24482-3-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 f2cf2e3..d9dec32 100644 (file)
--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -142,53 +142,17 @@ bool intel_hdcp_is_ksv_valid(u8 *ksv)
        return true;
 }
 
-/* Implements Part 2 of the HDCP authorization procedure */
 static
-int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
-                              const struct intel_hdcp_shim *shim)
+int intel_hdcp_validate_v_prime(struct intel_digital_port *intel_dig_port,
+                               const struct intel_hdcp_shim *shim,
+                               u8 *ksv_fifo, u8 num_downstream, u8 *bstatus)
 {
        struct drm_i915_private *dev_priv;
        u32 vprime, sha_text, sha_leftovers, rep_ctl;
-       u8 bstatus[2], num_downstream, *ksv_fifo;
        int ret, i, j, sha_idx;
 
        dev_priv = intel_dig_port->base.base.dev->dev_private;
 
-       ret = intel_hdcp_poll_ksv_fifo(intel_dig_port, shim);
-       if (ret) {
-               DRM_ERROR("KSV list failed to become ready (%d)\n", ret);
-               return ret;
-       }
-
-       ret = shim->read_bstatus(intel_dig_port, bstatus);
-       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;
-       }
-
-       /*
-        * When repeater reports 0 device count, HDCP1.4 spec allows disabling
-        * the HDCP encryption. That implies that repeater can't have its own
-        * display. As there is no consumption of encrypted content in the
-        * repeater with 0 downstream devices, we are failing the
-        * authentication.
-        */
-       num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
-       if (num_downstream == 0)
-               return -EINVAL;
-
-       ksv_fifo = kzalloc(num_downstream * DRM_HDCP_KSV_LEN, GFP_KERNEL);
-       if (!ksv_fifo)
-               return -ENOMEM;
-
-       ret = shim->read_ksv_fifo(intel_dig_port, num_downstream, ksv_fifo);
-       if (ret)
-               return ret;
-
        /* Process V' values from the receiver */
        for (i = 0; i < DRM_HDCP_V_PRIME_NUM_PARTS; i++) {
                ret = shim->read_v_prime_part(intel_dig_port, i, &vprime);
@@ -353,7 +317,8 @@ int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
                        return ret;
                sha_idx += sizeof(sha_text);
        } else {
-               DRM_ERROR("Invalid number of leftovers %d\n", sha_leftovers);
+               DRM_DEBUG_KMS("Invalid number of leftovers %d\n",
+                             sha_leftovers);
                return -EINVAL;
        }
 
@@ -381,14 +346,77 @@ int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
        if (intel_wait_for_register(dev_priv, HDCP_REP_CTL,
                                    HDCP_SHA1_COMPLETE,
                                    HDCP_SHA1_COMPLETE, 1)) {
-               DRM_ERROR("Timed out waiting for SHA1 complete\n");
+               DRM_DEBUG_KMS("Timed out waiting for SHA1 complete\n");
                return -ETIMEDOUT;
        }
        if (!(I915_READ(HDCP_REP_CTL) & HDCP_SHA1_V_MATCH)) {
-               DRM_ERROR("SHA-1 mismatch, HDCP failed\n");
+               DRM_DEBUG_KMS("SHA-1 mismatch, HDCP failed\n");
                return -ENXIO;
        }
 
+       return 0;
+}
+
+/* Implements Part 2 of the HDCP authorization procedure */
+static
+int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
+                              const struct intel_hdcp_shim *shim)
+{
+       u8 bstatus[2], num_downstream, *ksv_fifo;
+       int ret, i, tries = 3;
+
+       ret = intel_hdcp_poll_ksv_fifo(intel_dig_port, shim);
+       if (ret) {
+               DRM_ERROR("KSV list failed to become ready (%d)\n", ret);
+               return ret;
+       }
+
+       ret = shim->read_bstatus(intel_dig_port, bstatus);
+       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;
+       }
+
+       /*
+        * When repeater reports 0 device count, HDCP1.4 spec allows disabling
+        * the HDCP encryption. That implies that repeater can't have its own
+        * display. As there is no consumption of encrypted content in the
+        * repeater with 0 downstream devices, we are failing the
+        * authentication.
+        */
+       num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
+       if (num_downstream == 0)
+               return -EINVAL;
+
+       ksv_fifo = kzalloc(num_downstream * DRM_HDCP_KSV_LEN, GFP_KERNEL);
+       if (!ksv_fifo)
+               return -ENOMEM;
+
+       ret = shim->read_ksv_fifo(intel_dig_port, num_downstream, ksv_fifo);
+       if (ret)
+               return ret;
+
+       /*
+        * When V prime mismatches, DP Spec mandates re-read of
+        * V prime atleast twice.
+        */
+       for (i = 0; i < tries; i++) {
+               ret = intel_hdcp_validate_v_prime(intel_dig_port, shim,
+                                                 ksv_fifo, num_downstream,
+                                                 bstatus);
+               if (!ret)
+                       break;
+       }
+
+       if (i == tries) {
+               DRM_ERROR("V Prime validation failed.(%d)\n", ret);
+               return ret;
+       }
+
        DRM_DEBUG_KMS("HDCP is enabled (%d downstream devices)\n",
                      num_downstream);
        return 0;