From a369a7100da3b4f5c2269be25160653d2c7013fc Mon Sep 17 00:00:00 2001 From: Zwane Mwaikambo Date: Mon, 2 Apr 2007 12:14:12 +0200 Subject: [PATCH] [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: Zwane Mwaikambo Signed-off-by: Andi Kleen --- arch/i386/boot/video.S | 14 ++++++++++++++ arch/x86_64/boot/video.S | 14 ++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/arch/i386/boot/video.S b/arch/i386/boot/video.S index 2c5b5cc..8143c95 100644 --- a/arch/i386/boot/video.S +++ b/arch/i386/boot/video.S @@ -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 to see video modes available, " diff --git a/arch/x86_64/boot/video.S b/arch/x86_64/boot/video.S index d6ff88f..6090516 100644 --- a/arch/x86_64/boot/video.S +++ b/arch/x86_64/boot/video.S @@ -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 to see video modes available, " -- 2.7.4