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@gmail.com>
LKML-Reference: <20090701021307.GA3127@localhost.localdomain>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

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 */

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) {