[patch] Refine SCREEN_INFO sanity check for vgacon initialization.

[Gerd Hoffmann]

  Hi,

Checking video mode field only to see whenever SCREEN_INFO is
initialized is not enougth, in some cases it is zero although
a vga card is present.  Lets additionally check cols and lines.

Updates f82af20e1a028e16b9bb11da081fa1148d40fa6a, should go
into 2.6.22.

please apply,
  Gerd

Refine SCREEN_INFO sanity check for vgacon initialization.

Checking video mode field only to see whenever SCREEN_INFO is
initialized is not enougth, in some cases it is zero although
a vga card is present.  Lets additionally check cols and lines.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Alan <alan@xxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
---
 drivers/video/console/vgacon.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

Index: vanilla-2.6.21-git11/drivers/video/console/vgacon.c
===================================================================
--- vanilla-2.6.21-git11.orig/drivers/video/console/vgacon.c
+++ vanilla-2.6.21-git11/drivers/video/console/vgacon.c
@@ -368,9 +368,14 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
+	/* SCREEN_INFO initialized? */
+	if ((ORIG_VIDEO_MODE  == 0) &&
+	    (ORIG_VIDEO_LINES == 0) &&
+	    (ORIG_VIDEO_COLS  == 0))
+		goto no_vga;
+
 	/* VGA16 modes are not handled by VGACON */
-	if ((ORIG_VIDEO_MODE == 0x00) ||	/* SCREEN_INFO not initialized */
-	    (ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
+	if ((ORIG_VIDEO_MODE == 0x0D) ||	/* 320x200/4 */
 	    (ORIG_VIDEO_MODE == 0x0E) ||	/* 640x200/4 */
 	    (ORIG_VIDEO_MODE == 0x10) ||	/* 640x350/4 */
 	    (ORIG_VIDEO_MODE == 0x12) ||	/* 640x480/4 */