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Date: Mon, 24 Apr 2006 00:27:25 -0700
From: "Yum Rayan" <yum.rayan@gmail.com>
To: "Antonino A. Daplas" <adaplas@gmail.com>
Subject: Re: [RFC] VBE DDC bios call stalls boot
Cc: "Dave Jones" <davej@redhat.com>, linux-kernel@vger.kernel.org
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	 <20060423202428.GC14680@redhat.com> <444C1211.8090505@gmail.com>
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> > Is this how your patch looked when you tried this ?
>
> I've discovered that checking for availability does not give any added benefit,
> but this is the correct approach and I have to agree with this patch.

My patch was similar. I referenced
http://www.vesa.org/public/VBE/VBEDDC11.PDF. Differences were the
finer look up of the ambiguous status code and setting up ES:DI to be
NULL before call to INT 10h, as follows:

--- linux-2.6.15.4.a/arch/i386/boot/video.S	2006-02-09 23:22:48.000000000 -0800
+++ linux-2.6.15.4.b/arch/i386/boot/video.S	2006-04-24 00:07:08.000000000 -0700
@@ -1946,6 +1946,22 @@ store_edid:
 	rep
  	stosl

+	pushw	%es
+	movw	$0x4f15, %ax                    # report VBE/DDC capabilities
+	xorw	%bx, %bx
+	xorw	%cx, %cx
+	xorw	%di, %di
+	pushw	%di
+	popw	%es
+	int	$0x10
+	popw	%es
+
+	cmpb	$0x0, %ah			# function call failed
+	jne	no_edid
+
+	cmpb	$0x4f, %al			# function not supported
+	jne	no_edid
+
  	movw	$0x4f15, %ax                    # do VBE/DDC
  	movw	$0x01, %bx
  	movw	$0x00, %cx
@@ -1953,6 +1969,7 @@ store_edid:
  	movw	$0x140, %di
 	int	$0x10

+no_edid:
  	popw	%di				# restore all registers
  	popw	%dx
  	popw	%cx


> This option is new and not yet available in 2.6.15, so you may have
> to use your patch temporarily.

I was able to download a more recent kernel and configure
CONFIG_FB_FIRMWARE_EDID. Thanks.