linux-kernel - [PATCH] vgacon: checking for efi machine

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Date:	Thu, 06 Jan 2011 11:10:58 -0500
From:	Yannick Heneault <yannick_heneault@...rox.com>
To:	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	akpm@...ux-foundation.org
CC:	airlied@...hat.com, hpa@...or.com
Subject: [PATCH] vgacon: checking for efi machine

It seems there is a small problem of VGA palette corruption on EFI machine. When the kernel initializes the architecture, it checks if themachine is a EFI machine and assumes that a VGA console can exist. When it initialize the console in vgacon_startup it checks if itcan really use the VGA console. I think this is where a check ismissing. Currently, the function can fail if a VESA boot mode isdetected but not if a EFI boot mode was used. Thus, the function vgacon_startup doesn't fail and initialize thevideo card for a real VGA mode. This function change the first 16entries of the VGA palette. When the efifb driver kick-in, the paletteis not restored to default ramp value, thus the 16 first entry remain ina modified state. The following patch prevent this corruption.

Signed-off-by: Yannick Heneault<yheneaul@...rox.com>
---
diff -Nur linux-2.6.37-ori/drivers/video/console/vgacon.c linux-2.6.37/drivers/video/console/vgacon.c
--- linux-2.6.37-ori/drivers/video/console/vgacon.c	2011-01-04 19:50:19.000000000 -0500
+++ linux-2.6.37/drivers/video/console/vgacon.c	2011-01-06 10:38:24.713590593 -0500
@@ -375,7 +375,8 @@
  	u16 saved1, saved2;
  	volatile u16 *p;

-	if (screen_info.orig_video_isVGA == VIDEO_TYPE_VLFB) {
+	if (screen_info.orig_video_isVGA == VIDEO_TYPE_VLFB ||
+	    screen_info.orig_video_isVGA == VIDEO_TYPE_EFI) {
  	      no_vga:
  #ifdef CONFIG_DUMMY_CONSOLE
  		conswitchp =&dummy_con;

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