[PATCH] drm/edid: limit printk when facing bad edid

[j.glisse@gmail.com]

From: Jerome Glisse <jglisse@redhat.com>

Limit printing bad edid information at one time per connector.
Connector that are connected to a bad monitor/kvm will likely
stay connected to the same bad monitor/kvm and it makes no
sense to keep printing the bad edid message.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
---
 drivers/gpu/drm/drm_edid.c      | 22 ++++++++++++++--------
 drivers/gpu/drm/drm_edid_load.c |  6 ++++--
 include/drm/drm_crtc.h          |  3 ++-
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index a8743c3..7380ee3 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -158,7 +158,7 @@ MODULE_PARM_DESC(edid_fixup,
  * Sanity check the EDID block (base or extension).  Return 0 if the block
  * doesn't check out, or 1 if it's valid.
  */
-bool drm_edid_block_valid(u8 *raw_edid, int block)
+bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid)
 {
 	int i;
 	u8 csum = 0;
@@ -181,7 +181,9 @@ bool drm_edid_block_valid(u8 *raw_edid, int block)
 	for (i = 0; i < EDID_LENGTH; i++)
 		csum += raw_edid[i];
 	if (csum) {
-		DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum);
+		if (print_bad_edid) {
+			DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum);
+		}
 
 		/* allow CEA to slide through, switches mangle this */
 		if (raw_edid[0] != 0x02)
@@ -207,7 +209,7 @@ bool drm_edid_block_valid(u8 *raw_edid, int block)
 	return 1;
 
 bad:
-	if (raw_edid) {
+	if (raw_edid && print_bad_edid) {
 		printk(KERN_ERR "Raw EDID:\n");
 		print_hex_dump(KERN_ERR, " \t", DUMP_PREFIX_NONE, 16, 1,
 			       raw_edid, EDID_LENGTH, false);
@@ -231,7 +233,7 @@ bool drm_edid_is_valid(struct edid *edid)
 		return false;
 
 	for (i = 0; i <= edid->extensions; i++)
-		if (!drm_edid_block_valid(raw + i * EDID_LENGTH, i))
+		if (!drm_edid_block_valid(raw + i * EDID_LENGTH, i, true))
 			return false;
 
 	return true;
@@ -303,6 +305,7 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
 {
 	int i, j = 0, valid_extensions = 0;
 	u8 *block, *new;
+	bool print_bad_edid = !connector->bad_edid_counter || (drm_debug & DRM_UT_KMS);
 
 	if ((block = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
 		return NULL;
@@ -311,7 +314,7 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
 	for (i = 0; i < 4; i++) {
 		if (drm_do_probe_ddc_edid(adapter, block, 0, EDID_LENGTH))
 			goto out;
-		if (drm_edid_block_valid(block, 0))
+		if (drm_edid_block_valid(block, 0, print_bad_edid))
 			break;
 		if (i == 0 && drm_edid_is_zero(block, EDID_LENGTH)) {
 			connector->null_edid_counter++;
@@ -336,7 +339,7 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
 				  block + (valid_extensions + 1) * EDID_LENGTH,
 				  j, EDID_LENGTH))
 				goto out;
-			if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH, j)) {
+			if (drm_edid_block_valid(block + (valid_extensions + 1) * EDID_LENGTH, j, print_bad_edid)) {
 				valid_extensions++;
 				break;
 			}
@@ -359,8 +362,11 @@ drm_do_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter)
 	return block;
 
 carp:
-	dev_warn(connector->dev->dev, "%s: EDID block %d invalid.\n",
-		 drm_get_connector_name(connector), j);
+	if (print_bad_edid) {
+		dev_warn(connector->dev->dev, "%s: EDID block %d invalid.\n",
+			 drm_get_connector_name(connector), j);
+	}
+	connector->bad_edid_counter++;
 
 out:
 	kfree(block);
diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
index 66d4a28..14f46dd 100644
--- a/drivers/gpu/drm/drm_edid_load.c
+++ b/drivers/gpu/drm/drm_edid_load.c
@@ -123,6 +123,7 @@ static int edid_load(struct drm_connector *connector, char *name,
 	int fwsize, expected;
 	int builtin = 0, err = 0;
 	int i, valid_extensions = 0;
+	bool print_bad_edid = !connector->bad_edid_counter || (drm_debug & DRM_UT_KMS);
 
 	pdev = platform_device_register_simple(connector_name, -1, NULL, 0);
 	if (IS_ERR(pdev)) {
@@ -173,7 +174,8 @@ static int edid_load(struct drm_connector *connector, char *name,
 	}
 	memcpy(edid, fwdata, fwsize);
 
-	if (!drm_edid_block_valid(edid, 0)) {
+	if (!drm_edid_block_valid(edid, 0, print_bad_edid)) {
+		connector->bad_edid_counter++;
 		DRM_ERROR("Base block of EDID firmware \"%s\" is invalid ",
 		    name);
 		kfree(edid);
@@ -185,7 +187,7 @@ static int edid_load(struct drm_connector *connector, char *name,
 		if (i != valid_extensions + 1)
 			memcpy(edid + (valid_extensions + 1) * EDID_LENGTH,
 			    edid + i * EDID_LENGTH, EDID_LENGTH);
-		if (drm_edid_block_valid(edid + i * EDID_LENGTH, i))
+		if (drm_edid_block_valid(edid + i * EDID_LENGTH, i, print_bad_edid))
 			valid_extensions++;
 	}
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index bac55c2..1a2987b 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -594,6 +594,7 @@ struct drm_connector {
 	int video_latency[2];	/* [0]: progressive, [1]: interlaced */
 	int audio_latency[2];
 	int null_edid_counter; /* needed to workaround some HW bugs where we get all 0s */
+	unsigned bad_edid_counter;
 };
 
 /**
@@ -1038,7 +1039,7 @@ extern int drm_add_modes_noedid(struct drm_connector *connector,
 				int hdisplay, int vdisplay);
 
 extern int drm_edid_header_is_valid(const u8 *raw_edid);
-extern bool drm_edid_block_valid(u8 *raw_edid, int block);
+extern bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid);
 extern bool drm_edid_is_valid(struct edid *edid);
 struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 					   int hsize, int vsize, int fresh,
-- 
1.7.11.2