[PATCH 1/6] drm/i915: Add automated testing support for Displayport compliance testing

[Todd Previte <tprevite@gmail.com>]

Add the skeleton framework for supporting automation for Displayport compliance testing. This patch
adds the necessary framework for the source device to appropriately responded to test automation
requests from a sink device.

Signed-off-by: Todd Previte <tprevite@gmail.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 84 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index b5ec489..3bd1780 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3328,11 +3328,91 @@ intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
 				       sink_irq_vector, 1) == 1;
 }
 
+/* Displayport compliance testing - Link training */
+static uint8_t
+intel_dp_autotest_link_training(struct intel_dp *intel_dp)
+{
+	uint8_t test_result = DP_TEST_NAK;
+	return test_result;
+}
+
+/* Displayport compliance testing - Video pattern testing */
+static uint8_t
+intel_dp_autotest_video_pattern(struct intel_dp *intel_dp)
+{
+	uint8_t test_result = DP_TEST_NAK;
+	return test_result;
+}
+
+/* Displayport compliance testing - EDID operations */
+static uint8_t
+intel_dp_autotest_edid(struct intel_dp *intel_dp)
+{
+	uint8_t test_result = DP_TEST_NAK;
+	return test_result;
+}
+
+/* Displayport compliance testing - PHY pattern testing */
+static uint8_t
+intel_dp_autotest_phy_pattern(struct intel_dp *intel_dp)
+{
+	uint8_t test_result = DP_TEST_NAK;
+	return test_result;
+}
+
+/* Displayport compliance testing - Fast AUX transactions (optional) */
+static uint8_t
+intel_dp_autotest_faux_pattern(struct intel_dp *intel_dp)
+{
+        uint8_t test_result = DP_TEST_NAK;
+		printk("Displayport: Fast AUX (FAUX) not supported.\n");
+        return test_result;
+}
+
 static void
 intel_dp_handle_test_request(struct intel_dp *intel_dp)
 {
-	/* NAK by default */
-	drm_dp_dpcd_writeb(&intel_dp->aux, DP_TEST_RESPONSE, DP_TEST_NAK);
+	uint8_t response = DP_TEST_NAK;
+	uint8_t rxdata = 0;
+	int ret = 0;
+
+	DRM_DEBUG_KMS("Displayport: Received automated test request\n");
+	/* Read DP_TEST_REQUEST register to identify the requested test */
+	ret = drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_REQUEST, &rxdata, 1);
+
+	/* Determine which test has been requested */
+	switch (rxdata) {
+		/* ACK/NAK response based on test function response
+		   Unimplemented/unsupported tests will NAK */
+		case DP_TEST_LINK_TRAINING:
+			DRM_DEBUG_KMS("Displayport: Executing LINK_TRAINING request\n");
+			response = intel_dp_autotest_link_training(intel_dp);
+			break;
+		case DP_TEST_LINK_VIDEO_PATTERN:
+			DRM_DEBUG_KMS("Displayport: Executing TEST_PATTERN request\n");
+			response = intel_dp_autotest_video_pattern(intel_dp);
+			break;
+		case DP_TEST_LINK_EDID_READ:
+			DRM_DEBUG_KMS("Displayport: Executing EDID request\n");
+			response = intel_dp_autotest_edid(intel_dp);
+			break;
+		case DP_TEST_LINK_PHY_TEST_PATTERN:
+			DRM_DEBUG_KMS("Displayport: Executing PHY_PATTERN request\n");
+			response = intel_dp_autotest_phy_pattern(intel_dp);
+			break;
+			/* FAUX is optional in DP 1.2*/
+		case DP_TEST_LINK_FAUX_PATTERN:
+			DRM_DEBUG_KMS("Displayport: Executing FAUX_PATTERN request \n");
+			response = intel_dp_autotest_faux_pattern(intel_dp);
+			break;
+		/* Unsupported test case or something went wrong */
+		default:
+			/* Log error here for unhandled test request */
+			DRM_DEBUG_KMS("Displayport: Error - unhandled automated test request\n");
+			break;
+	}
+	/* Send the response from the test result */
+	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TEST_RESPONSE, &response, 1);
 }
 
 /*
-- 
1.9.1