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    Subject[PATCH] 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: Zwane Mwaikambo <zwane@infradead.org>

    Index: linux-2.6.20-rc6-mm1/arch/i386/boot/video.S
    ===================================================================
    RCS file: /home/cvsroot/linux-2.6.20-rc6-mm1/arch/i386/boot/video.S,v
    retrieving revision 1.1.1.1
    diff -u -p -B -r1.1.1.1 video.S
    --- linux-2.6.20-rc6-mm1/arch/i386/boot/video.S 30 Jan 2007 05:28:31 -0000 1.1.1.1
    +++ linux-2.6.20-rc6-mm1/arch/i386/boot/video.S 15 Feb 2007 16:27:32 -0000
    @@ -1945,6 +1945,20 @@ store_edid:
    rep
    stosl

    + pushw %es
    + pushw %ds
    + popw %es
    + leaw modelist+1024, %di
    + movw $0x4f00, %ax
    + int $0x10
    + popw %es
    +
    + cmpw $0x004f, %ax
    + jne no_edid
    +
    + cmpw $0x0102, 4(%di) # only do EDID on > 1.2
    + je no_edid
    +
    pushw %es # save ES
    xorw %di, %di # Report Capability
    pushw %di
    Index: linux-2.6.20-rc6-mm1/arch/x86_64/boot/video.S
    ===================================================================
    RCS file: /home/cvsroot/linux-2.6.20-rc6-mm1/arch/x86_64/boot/video.S,v
    retrieving revision 1.1.1.1
    diff -u -p -B -r1.1.1.1 video.S
    --- linux-2.6.20-rc6-mm1/arch/x86_64/boot/video.S 30 Jan 2007 05:28:36 -0000 1.1.1.1
    +++ linux-2.6.20-rc6-mm1/arch/x86_64/boot/video.S 15 Feb 2007 16:27:32 -0000
    @@ -1945,6 +1945,20 @@ store_edid:
    rep
    stosl

    + pushw %es
    + pushw %ds
    + popw %es
    + leaw modelist+1024, %di
    + movw $0x4f00, %ax
    + int $0x10
    + popw %es
    +
    + cmpw $0x004f, %ax
    + jne no_edid
    +
    + cmpw $0x0102, 4(%di) # only do EDID on > 1.2
    + je no_edid
    +
    pushw %es # save ES
    xorw %di, %di # Report Capability
    pushw %di
    -
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