Re: [RFC] VBE DDC bios call stalls boot

[Dave Jones]

On Sun, Apr 23, 2006 at 12:08:27PM -0700, Yum Rayan wrote:

 > There is a bios call to check if read EDID is supported. My first
 > thought was that before doing read EDID, video.S should first check to
 > see if the hardware supports the read EDID feature. Unfortunately that
 > bios call too ends up in the woods until I physically
 > disconnect/reconnect my CPU video output that feeds into the KVM.

Is this how your patch looked when you tried this ?

		Dave

--- linux-2.6.15/arch/i386/boot/video.S~	2006-01-06 01:26:06.000000000 -0500
+++ linux-2.6.15/arch/i386/boot/video.S	2006-01-06 01:28:40.000000000 -0500
@@ -1951,9 +1951,18 @@ store_edid:
 	stosl
 
 	movw	$0x4f15, %ax                    # do VBE/DDC
-	movw	$0x01, %bx
+	movw	$0x00, %bx                      # INSTALLATION CHECK / CAPABILITIES
 	movw	$0x00, %cx
-	movw    $0x00, %dx
+	movw	$0x00, %dx
+	movw	$0x140, %di
+	int		$0x10
+	cmpb	$0x01, %ah
+	je		no_edid
+
+	movw	$0x4f15, %ax                    # do VBE/DDC
+	movw	$0x01, %bx                      # READ_EDID
+	movw	$0x00, %cx
+	movw	$0x00, %dx
 	movw	$0x140, %di
 	int	$0x10
 
--- linux-2.6.15/arch/i386/boot/video.S~	2006-01-06 02:55:20.000000000 -0500
+++ linux-2.6.15/arch/i386/boot/video.S	2006-01-06 02:55:28.000000000 -0500
@@ -1966,6 +1966,7 @@ store_edid:
 	movw	$0x140, %di
 	int	$0x10
 
+no_edid:
 	popw	%di				# restore all registers
 	popw	%dx
 	popw	%cx

-- 
http://www.codemonkey.org.uk
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