[PATCH v2 1/2] drm: Add support for DP 1.4 Compliance edid corruption test 4.2.2.6

Jerry (Fangzhi) Zuo Jerry.Zuo at amd.com
Fri Nov 1 19:38:39 UTC 2019


DP 1.4 edid corruption test requires source DUT to write calculated
CRC, not the corrupted CRC from reference sink.

Return the calculated CRC back, and initiate the required sequence.

-v2: Have separate routine for returning real CRC

Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo at amd.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 36 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_edid.c      | 14 ++++++++++++++
 include/drm/drm_connector.h     |  7 +++++++
 include/drm/drm_dp_helper.h     |  3 +++
 4 files changed, 60 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index ffc68d305afe..75dbd30c62a7 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -336,6 +336,42 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
 
+/**
+  * drm_dp_send_bad_edid_checksum() - send back real edid checksum value
+  * @aux: DisplayPort AUX channel
+  * @bad_edid_checksum: real edid checksum for the last block
+  *
+  * Returns true on success
+  */
+bool drm_dp_send_bad_edid_checksum(struct drm_dp_aux *aux,
+                                u8 bad_edid_checksum)
+{
+        u8 link_edid_read = 0, auto_test_req = 0;
+        u8 test_resp = 0;
+
+        drm_dp_dpcd_read(aux, DP_DEVICE_SERVICE_IRQ_VECTOR, &auto_test_req, 1);
+        auto_test_req &= DP_AUTOMATED_TEST_REQUEST;
+
+        drm_dp_dpcd_read(aux, DP_TEST_REQUEST, &link_edid_read, 1);
+        link_edid_read &= DP_TEST_LINK_EDID_READ;
+
+        if (!auto_test_req || !link_edid_read) {
+                DRM_DEBUG_KMS("Source DUT does not support TEST_EDID_READ\n");
+                return false;
+        }
+
+        drm_dp_dpcd_write(aux, DP_DEVICE_SERVICE_IRQ_VECTOR, &auto_test_req, 1);
+
+        /* send back checksum for the last edid extension block data */
+        drm_dp_dpcd_write(aux, DP_TEST_EDID_CHECKSUM, &bad_edid_checksum, 1);
+
+        test_resp |= DP_TEST_EDID_CHECKSUM_WRITE;
+        drm_dp_dpcd_write(aux, DP_TEST_RESPONSE, &test_resp, 1);
+
+        return true;
+}
+EXPORT_SYMBOL(drm_dp_send_bad_edid_checksum);
+
 /**
  * drm_dp_link_probe() - probe a DisplayPort link for capabilities
  * @aux: DisplayPort AUX channel
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 82a4ceed3fcf..0598314e3f46 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1354,6 +1354,17 @@ static int drm_edid_block_checksum(const u8 *raw_edid)
 	return csum;
 }
 
+static int drm_edid_block_real_checksum(const u8 *raw_edid)
+{
+	int i;
+	u8 csum = 0;
+
+	for (i = 0; i < EDID_LENGTH - 1; i++)
+		csum += raw_edid[i];
+
+	return (0x100 - csum);
+}
+
 static bool drm_edid_is_zero(const u8 *in_edid, int length)
 {
 	if (memchr_inv(in_edid, 0, length))
@@ -1572,6 +1583,9 @@ static void connector_bad_edid(struct drm_connector *connector,
 			       prefix, DUMP_PREFIX_NONE, 16, 1,
 			       block, EDID_LENGTH, false);
 	}
+
+	/* Calculate real checksum for the last edid extension block data */
+	connector->bad_edid_checksum = drm_edid_block_real_checksum(edid + edid[0x7e] * EDID_LENGTH);
 }
 
 /* Get override or firmware EDID */
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 681cb590f952..8442461542b9 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1345,6 +1345,13 @@ struct drm_connector {
 	 * rev1.1 4.2.2.6
 	 */
 	bool edid_corrupt;
+	/**
+         * @bad_edid_checksum: real edid checksum value for corrupted edid block.
+         * Required in Displayport 1.4 compliance testing
+         * rev1.1 4.2.2.6
+         */
+        uint8_t bad_edid_checksum;
+
 
 	/** @debugfs_entry: debugfs directory for this connector */
 	struct dentry *debugfs_entry;
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 5a795075d5da..2a7e54bebb18 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1383,6 +1383,9 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 				 u8 status[DP_LINK_STATUS_SIZE]);
 
+bool drm_dp_send_bad_edid_checksum(struct drm_dp_aux *aux,
+				u8 bad_edid_checksum);
+
 /*
  * DisplayPort link
  */
-- 
2.14.1



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