drm/kms: add a module param to disable strict EDID checking

Commit Message

Alex Deucher Jan. 4, 2011, 11 p.m. UTC

None

Comments

Antti Palosaari July 16, 2011, 5:48 p.m. UTC | #1

Hey,
Could you say what's status of fixing that problem? I see Alex patch is 
not included to the Kernel for the some reason.

Could you point out what is recommended workaround for that bug as now?

I have that known bad behaving Acer AL2216W monitor...


regards
Antti

Patch

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index a245d17..4794faa 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -128,8 +128,8 @@  static const u8 edid_header[] = {
 };
 
 /*
- * Sanity check the EDID block (base or extension).  Return 0 if the block
- * doesn't check out, or 1 if it's valid.
+ * Sanity check the EDID block (base or extension).  Return false if the block
+ * doesn't check out, or true if it's valid.
  */
 static bool
 drm_edid_block_valid(u8 *raw_edid)
@@ -160,8 +160,10 @@  drm_edid_block_valid(u8 *raw_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)
-			goto bad;
+		if (raw_edid[0] != 0x02) {
+			if (drm_edid_strict)
+				goto bad;
+		}
 	}
 
 	/* per-block-type checks */
@@ -169,7 +171,8 @@  drm_edid_block_valid(u8 *raw_edid)
 	case 0: /* base */
 		if (edid->version != 1) {
 			DRM_ERROR("EDID has major version %d, instead of 1\n", edid->version);
-			goto bad;
+			if (drm_edid_strict)
+				goto bad;
 		}
 
 		if (edid->revision > 4)
@@ -180,7 +183,7 @@  drm_edid_block_valid(u8 *raw_edid)
 		break;
 	}
 
-	return 1;
+	return true;
 
 bad:
 	if (raw_edid) {
@@ -188,7 +191,7 @@  bad:
 		print_hex_dump_bytes(KERN_ERR, DUMP_PREFIX_NONE, raw_edid, EDID_LENGTH);
 		printk("\n");
 	}
-	return 0;
+	return false;
 }
 
 /**
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index d59edc1..8b4530e 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -46,16 +46,21 @@  EXPORT_SYMBOL(drm_vblank_offdelay);
 unsigned int drm_timestamp_precision = 20;  /* Default to 20 usecs. */
 EXPORT_SYMBOL(drm_timestamp_precision);
 
+int drm_edid_strict = 1;	/* 0 to disable strict edid conformance */
+EXPORT_SYMBOL(drm_edid_strict);
+
 MODULE_AUTHOR(CORE_AUTHOR);
 MODULE_DESCRIPTION(CORE_DESC);
 MODULE_LICENSE("GPL and additional rights");
 MODULE_PARM_DESC(debug, "Enable debug output");
 MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
 MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
+MODULE_PARM_DESC(edid_strict, "Strict EDID checks (0 = disable)");
 
 module_param_named(debug, drm_debug, int, 0600);
 module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
 module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
+module_param_named(edid_strict, drm_edid_strict, int, 0600);
 
 struct idr drm_minors_idr;
 
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 0f14f94..fd99988 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1430,6 +1430,8 @@  extern unsigned int drm_debug;
 extern unsigned int drm_vblank_offdelay;
 extern unsigned int drm_timestamp_precision;
 
+extern int drm_edid_strict;
+
 extern struct class *drm_class;
 extern struct proc_dir_entry *drm_proc_root;
 extern struct dentry *drm_debugfs_root;