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Commit 1e274a58 authored by H. Peter Anvin's avatar H. Peter Anvin
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x86, setup: un-resequence mode setting for VGA 80x34 and 80x60 modes 



Impact: Fixes these modes on at least one system

The rewrite of the setup code into C resequenced the font setting and
register reprogramming phases of configuring nonstandard VGA modes
which use 480 scan lines in text mode.  However, there exists at least
one board (Micro-Star MS-7383 version 2.0) on which this resequencing
causes an unusable display.

Revert to the original sequencing: set up 480-line mode, install the
font, and then adjust the vertical end register appropriately.

This failure was masked by the fact that the 480-line setup was broken
until checkin 5f641356 (therefore this
is not a -stable candidate bug fix.)

Reported-by: default avatarAndi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent f7d7f866

arch/x86/boot/video-vga.c

+23 −10
Original line number Diff line number Diff line
@@ -129,22 +129,18 @@ u16 vga_crtc(void) 
	return (inb(0x3cc) & 1) ? 0x3d4 : 0x3b4;

}



static void vga_set_480_scanlines(int lines)

static void vga_set_480_scanlines(void)

{

	u16 crtc;		/* CRTC base address */

	u8  csel;		/* CRTC miscellaneous output register */

	u8  ovfw;		/* CRTC overflow register */

	int end = lines-1;



	crtc = vga_crtc();



	ovfw = 0x3c | ((end >> (8-1)) & 0x02) | ((end >> (9-6)) & 0x40);



	out_idx(0x0c, crtc, 0x11); /* Vertical sync end, unlock CR0-7 */

	out_idx(0x0b, crtc, 0x06); /* Vertical total */

	out_idx(ovfw, crtc, 0x07); /* Vertical overflow */

	out_idx(0x3e, crtc, 0x07); /* Vertical overflow */

	out_idx(0xea, crtc, 0x10); /* Vertical sync start */

	out_idx(end,  crtc, 0x12); /* Vertical display end */

	out_idx(0xdf, crtc, 0x12); /* Vertical display end */

	out_idx(0xe7, crtc, 0x15); /* Vertical blank start */

	out_idx(0x04, crtc, 0x16); /* Vertical blank end */

	csel = inb(0x3cc);
@@ -153,21 +149,38 @@ static void vga_set_480_scanlines(int lines) 
	outb(csel, 0x3c2);

}



static void vga_set_vertical_end(int lines)

{

	u16 crtc;		/* CRTC base address */

	u8  ovfw;		/* CRTC overflow register */

	int end = lines-1;



	crtc = vga_crtc();



	ovfw = 0x3c | ((end >> (8-1)) & 0x02) | ((end >> (9-6)) & 0x40);



	out_idx(ovfw, crtc, 0x07); /* Vertical overflow */

	out_idx(end,  crtc, 0x12); /* Vertical display end */

}



static void vga_set_80x30(void)

{

	vga_set_480_scanlines(30*16);

	vga_set_480_scanlines();

	vga_set_vertical_end(30*16);

}



static void vga_set_80x34(void)

{

	vga_set_480_scanlines();

	vga_set_14font();

	vga_set_480_scanlines(34*14);

	vga_set_vertical_end(34*14);

}



static void vga_set_80x60(void)

{

	vga_set_480_scanlines();

	vga_set_8font();

	vga_set_480_scanlines(60*8);

	vga_set_vertical_end(60*8);

}



static int vga_set_mode(struct mode_info *mode)