[PATCH 3/5] i386: Set 6-bit DAC channel properties in vesa video setup
DORMANTno replies
From: "Antonino A. Daplas" <adaplas@gmail.com>
Date: 2007-06-05 11:28:57
Subsystem:
the rest · Maintainer:
Linus Torvalds
If the video BIOS is not capable of switching or failed to switch the hardware to 8-bit DAC, the channel properties are not set. This leads to a blank (all black) display with vesafb at 8 bpp. Fix by defaulting to a 6-bit DAC. Signed-off-by: Antonino Daplas <adaplas@gmail.com> --- arch/i386/boot/video-vesa.c | 25 +++++++++++++------------ 1 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/arch/i386/boot/video-vesa.c b/arch/i386/boot/video-vesa.c
index 26d66a7..3c21bd7 100644
--- a/arch/i386/boot/video-vesa.c
+++ b/arch/i386/boot/video-vesa.c@@ -153,19 +153,21 @@ static int vesa_set_mode(struct mode_inf /* Switch DAC to 8-bit mode */ static void vesa_dac_set_8bits(void) { - u16 ax, bx; - u8 dac_size; + u8 dac_size = 6; - ax = 0x4f08; - bx = 0x0800; - asm volatile(INT10 - : "+a" (ax), "+b" (bx) - : : "ecx", "edx", "esi", "edi"); + /* If possible, switch the DAC to 8-bit mode */ + if (vginfo.capabilities & 1) { + u16 ax, bx; - if (ax != 0x004f) - return; + ax = 0x4f08; + bx = 0x0800; + asm volatile(INT10 + : "+a" (ax), "+b" (bx) + : : "ecx", "edx", "esi", "edi"); - dac_size = bx >> 8; + if (ax == 0x004f) + dac_size = bx >> 8; + } /* Set the color sizes to the DAC size, and offsets to 0 */ boot_params.screen_info.red_size = dac_size;
@@ -219,8 +221,7 @@ static void vesa_store_mode_params_graph /* General parameters */ boot_params.screen_info.lfb_size = vginfo.total_memory; - /* If possible, switch the DAC to 8-bit mode */ - if (vminfo.bpp <= 8 && (vginfo.capabilities & 1)) + if (vminfo.bpp <= 8) vesa_dac_set_8bits(); vesa_store_pm_info(); -------------------------------------------------------------------------
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