linux-kernel - [PATCH] x86: fix usage of bios intcall()

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Date:	Wed, 1 Jul 2009 11:13:07 +0900
From:	Akinobu Mita <akinobu.mita@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, tglx@...utronix.de, hpa@...or.com
Subject: [PATCH] x86: fix usage of bios intcall()

Some intcall() misuses the input biosregs as output in
cf06de7b9cdd3efee7a59dced1977b3c21d43732

This fixes the problem vga=ask boot option doesn't show enough modes.

Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
---
 arch/x86/boot/video-bios.c |    3 +--
 arch/x86/boot/video-vesa.c |    4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index d660be4..49e0c18 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.c
@@ -37,14 +37,13 @@ static int set_bios_mode(u8 mode)
 	ireg.al = mode;		/* AH=0x00 Set Video Mode */
 	intcall(0x10, &ireg, NULL);
 
-
 	ireg.ah = 0x0f;		/* Get Current Video Mode */
 	intcall(0x10, &ireg, &oreg);
 
 	do_restore = 1;		/* Assume video contents were lost */
 
 	/* Not all BIOSes are clean with the top bit */
-	new_mode = ireg.al & 0x7f;
+	new_mode = oreg.al & 0x7f;
 
 	if (new_mode == mode)
 		return 0;	/* Mode change OK */
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index c700147..275dd17 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -45,7 +45,7 @@ static int vesa_probe(void)
 	ireg.di = (size_t)&vginfo;
 	intcall(0x10, &ireg, &oreg);
 
-	if (ireg.ax != 0x004f ||
+	if (oreg.ax != 0x004f ||
 	    vginfo.signature != VESA_MAGIC ||
 	    vginfo.version < 0x0102)
 		return 0;	/* Not present */
@@ -70,7 +70,7 @@ static int vesa_probe(void)
 		ireg.di = (size_t)&vminfo;
 		intcall(0x10, &ireg, &oreg);
 
-		if (ireg.ax != 0x004f)
+		if (oreg.ax != 0x004f)
 			continue;
 
 		if ((vminfo.mode_attr & 0x15) == 0x05) {
--
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