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Commit a369a710 authored by Zwane Mwaikambo's avatar Zwane Mwaikambo Committed by Andi Kleen
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[PATCH] x86: Don't probe for DDC on VBE1.2 

VBE1.2 doesn't support function 15h (DDC) resulting in a 'hang' whilst
uncompressing kernel with some video cards. Make sure we check VBE version
before fiddling around with DDC.

http://bugzilla.kernel.org/show_bug.cgi?id=1458



Opened: 2003-10-30 09:12 Last update: 2007-02-13 22:03

Much thanks to Tobias Hain for help in testing and investigating the bug.
Tested on;

i386, Chips & Technologies 65548 VESA VBE 1.2
CONFIG_VIDEO_SELECT=Y
CONFIG_FIRMWARE_EDID=Y

Untested on x86_64.

Signed-off-by: default avatarZwane Mwaikambo <zwane@infradead.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 0fb2ebfc

arch/i386/boot/video.S

+14 −0
Original line number Diff line number Diff line
@@ -571,6 +571,16 @@ setr1: lodsw 
	jmp	_m_s



check_vesa:

#ifdef CONFIG_FIRMWARE_EDID

	leaw	modelist+1024, %di

	movw	$0x4f00, %ax

	int	$0x10

	cmpw	$0x004f, %ax

	jnz	setbad



	movw	4(%di), %ax

	movw	%ax, vbe_version

#endif

	leaw	modelist+1024, %di

	subb	$VIDEO_FIRST_VESA>>8, %bh

	movw	%bx, %cx			# Get mode information structure
@@ -1945,6 +1955,9 @@ store_edid: 
	rep

	stosl



	cmpw	$0x0200, vbe_version		# only do EDID on >= VBE2.0

	jl	no_edid



	pushw   %es				# save ES

	xorw    %di, %di                        # Report Capability

	pushw   %di
@@ -1987,6 +2000,7 @@ do_restore: .byte 0 # Screen contents altered during mode change 
svga_prefix:	.byte	VIDEO_FIRST_BIOS>>8	# Default prefix for BIOS modes

graphic_mode:	.byte	0	# Graphic mode with a linear frame buffer

dac_size:	.byte	6	# DAC bit depth

vbe_version:	.word	0	# VBE bios version



# Status messages

keymsg:		.ascii	"Press <RETURN> to see video modes available, "

arch/x86_64/boot/video.S

+14 −0
Original line number Diff line number Diff line
@@ -571,6 +571,16 @@ setr1: lodsw 
	jmp	_m_s



check_vesa:

#ifdef CONFIG_FIRMWARE_EDID

	leaw	modelist+1024, %di

	movw	$0x4f00, %ax

	int	$0x10

	cmpw	$0x004f, %ax

	jnz	setbad



	movw	4(%di), %ax

	movw	%ax, vbe_version

#endif

	leaw	modelist+1024, %di

	subb	$VIDEO_FIRST_VESA>>8, %bh

	movw	%bx, %cx			# Get mode information structure
@@ -1945,6 +1955,9 @@ store_edid: 
	rep

	stosl



	cmpw	$0x0200, vbe_version		# only do EDID on >= VBE2.0

	jl	no_edid



	pushw   %es				# save ES

	xorw    %di, %di                        # Report Capability

	pushw   %di
@@ -1987,6 +2000,7 @@ do_restore: .byte 0 # Screen contents altered during mode change 
svga_prefix:	.byte	VIDEO_FIRST_BIOS>>8	# Default prefix for BIOS modes

graphic_mode:	.byte	0	# Graphic mode with a linear frame buffer

dac_size:	.byte	6	# DAC bit depth

vbe_version:	.word	0	# VBE bios version



# Status messages

keymsg:		.ascii	"Press <RETURN> to see video modes available, "