Attachment 41654 Details for Bug 31943 – add edid strict option

[patch] add edid strict option

0001-drm-kms-add-a-module-param-to-disable-strict-EDID-ch.patch (text/plain), 3.95 KB, created by Alex Deucher on 2011-01-04 15:04:38 UTC

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Creator: Alex Deucher

Created: 2011-01-04 15:04:38 UTC

Size: 3.95 KB

patch

obsolete

>From 9b9e7e5822f45368066eaa9edb8a054446cef4a6 Mon Sep 17 00:00:00 2001
>From: Alex Deucher <alexdeucher@gmail.com>
>Date: Tue, 4 Jan 2011 17:47:40 -0500
>Subject: [PATCH] drm/kms: add a module param to disable strict EDID checking
>
>Lots of EDIDs have bad checksums or bad version numbers, but
>have otherwise good data in them.  The current code rejects
>them which results in bad modes or blank screens in some cases.
>This patch adds a new module parameter, edid_strict, to drm.ko.
>It defaults to 1 (strict conformance, the current behavior),
>but if the user sets it to 0, it will bypass the checks and
>accept the EDID.
>
>Related bugs:
>https://bugs.freedesktop.org/show_bug.cgi?id=31943
>https://bugs.freedesktop.org/show_bug.cgi?id=27708
>https://bugzilla.kernel.org/show_bug.cgi?id=25052
>
>Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
>Cc: Adam Jackson <ajax@redhat.com>
>---
> drivers/gpu/drm/drm_edid.c |   17 ++++++++++-------
> drivers/gpu/drm/drm_stub.c |    5 +++++
> include/drm/drmP.h         |    2 ++
> 3 files changed, 17 insertions(+), 7 deletions(-)
>
>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;
>-- 
>1.7.1.1
>

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