[PATCH v3] drm/edid: Only print the bad edid when aborting

[Chris Wilson]

Currently, if drm.debug is enabled, we get a DRM_ERROR message on the
intermediate edid reads. This causes transient failures in CI which
flags up the sporadic EDID read failures, which are recovered by
rereading the EDID automatically. This patch combines the reporting done
by drm_do_get_edid() itself with the bad block printing from
get_edid_block(), into a single warning associated with the connector
once all attempts to retrieve the EDID fail.

v2: Print the whole EDID, marking up the bad/zero blocks. This requires
recording the whole of the raw edid, then a second pass to reduce it to
the valid extensions.
v3: Fix invalid/valid extension fumble.

References: https://bugs.freedesktop.org/show_bug.cgi?id=98228
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_edid.c | 79 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 95de47ba1e77..9506933b41cd 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1260,6 +1260,34 @@ drm_do_probe_ddc_edid(void *data, u8 *buf, unsigned int block, size_t len)
 	return ret == xfers ? 0 : -1;
 }
 
+static void connector_bad_edid(struct drm_connector *connector,
+			       u8 *edid, int num_blocks)
+{
+	int i;
+
+	if (connector->bad_edid_counter++ && !(drm_debug & DRM_UT_KMS))
+		return;
+
+	dev_warn(connector->dev->dev,
+		 "%s: EDID is invalid:\n",
+		 connector->name);
+	for (i = 0; i < num_blocks; i++) {
+		u8 *block = edid + i * EDID_LENGTH;
+		char prefix[20];
+
+		if (drm_edid_is_zero(block, EDID_LENGTH))
+			sprintf(prefix, "\t[%02x] ZERO ", i);
+		else if (!drm_edid_block_valid(block, i, false, NULL))
+			sprintf(prefix, "\t[%02x] BAD  ", i);
+		else
+			sprintf(prefix, "\t[%02x] GOOD ", i);
+
+		print_hex_dump(KERN_WARNING,
+			       prefix, DUMP_PREFIX_NONE, 16, 1,
+			       block, EDID_LENGTH, false);
+	}
+}
+
 /**
  * drm_do_get_edid - get EDID data using a custom EDID block read function
  * @connector: connector we're probing
@@ -1283,7 +1311,6 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 {
 	int i, j = 0, valid_extensions = 0;
 	u8 *edid, *new;
-	bool print_bad_edid = !connector->bad_edid_counter || (drm_debug & DRM_UT_KMS);
 
 	if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
 		return NULL;
@@ -1292,7 +1319,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 	for (i = 0; i < 4; i++) {
 		if (get_edid_block(data, edid, 0, EDID_LENGTH))
 			goto out;
-		if (drm_edid_block_valid(edid, 0, print_bad_edid,
+		if (drm_edid_block_valid(edid, 0, false,
 					 &connector->edid_corrupt))
 			break;
 		if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) {
@@ -1304,54 +1331,60 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 		goto carp;
 
 	/* if there's no extensions, we're done */
-	if (edid[0x7e] == 0)
+	valid_extensions = edid[0x7e];
+	if (valid_extensions == 0)
 		return (struct edid *)edid;
 
-	new = krealloc(edid, (edid[0x7e] + 1) * EDID_LENGTH, GFP_KERNEL);
+	new = krealloc(edid, (valid_extensions + 1) * EDID_LENGTH, GFP_KERNEL);
 	if (!new)
 		goto out;
 	edid = new;
 
 	for (j = 1; j <= edid[0x7e]; j++) {
-		u8 *block = edid + (valid_extensions + 1) * EDID_LENGTH;
+		u8 *block = edid + j * EDID_LENGTH;
 
 		for (i = 0; i < 4; i++) {
 			if (get_edid_block(data, block, j, EDID_LENGTH))
 				goto out;
-			if (drm_edid_block_valid(block, j,
-						 print_bad_edid, NULL)) {
-				valid_extensions++;
+			if (drm_edid_block_valid(block, j, false, NULL))
 				break;
-			}
 		}
 
-		if (i == 4 && print_bad_edid) {
-			dev_warn(connector->dev->dev,
-			 "%s: Ignoring invalid EDID block %d.\n",
-			 connector->name, j);
-
-			connector->bad_edid_counter++;
-		}
+		if (i == 4)
+			valid_extensions--;
 	}
 
 	if (valid_extensions != edid[0x7e]) {
+		u8 *base;
+
+		connector_bad_edid(connector, edid, edid[0x7e] + 1);
+
 		edid[EDID_LENGTH-1] += edid[0x7e] - valid_extensions;
 		edid[0x7e] = valid_extensions;
-		new = krealloc(edid, (valid_extensions + 1) * EDID_LENGTH, GFP_KERNEL);
+
+		new = kmalloc((valid_extensions + 1) * EDID_LENGTH, GFP_KERNEL);
 		if (!new)
 			goto out;
+
+		base = new;
+		for (i = 0; i <= edid[0x7e]; i++) {
+			u8 *block = edid + i * EDID_LENGTH;
+
+			if (!drm_edid_block_valid(block, i, false, NULL))
+				continue;
+
+			memcpy(base, block, EDID_LENGTH);
+			base += EDID_LENGTH;
+		}
+
+		kfree(edid);
 		edid = new;
 	}
 
 	return (struct edid *)edid;
 
 carp:
-	if (print_bad_edid) {
-		dev_warn(connector->dev->dev, "%s: EDID block %d invalid.\n",
-			 connector->name, j);
-	}
-	connector->bad_edid_counter++;
-
+	connector_bad_edid(connector, edid, 1);
 out:
 	kfree(edid);
 	return NULL;
-- 
2.10.1