From: Jarod Wilson <jwilson@redhat.com>
Date: Thu, 25 Oct 2007 11:31:35 -0400
Subject: [ia64] fix vga corruption with term blanking disabled
Message-id: 4720B6D7.8010804@redhat.com
O-Subject: [RHEL5.2 PATCH] fix ia64 vga corruption with term blanking disabled (version 2)
Bugzilla: 291421

Bugzilla #291421: [5.2] Graphic corruption issue
https://bugzilla.redhat.com/show_bug.cgi?id=291421

Description
-----------
If console blanking is disabled (setterm -blank 0), attempting to write
data out to /dev/console can result in video corruption.

Test status
-----------
1. enable VGA console, disable serial console (if any)
2. boot into run level 3 and login as root
3. disable console blanking (setterm -blank 0)
4. startx
5. shutdown X
6. startx again
7. open the gnome-terminal and redirect some output to /dev/console.

With 2.6.18-53.el5.ia64 on my ia64 workstation, vga goes out to lunch. X
pegs the cpu and the image on screen is frozen. I can ssh in and kill X,
but the on screen image remains frozen until a reboot. A kernel with the
attached patch has no such problem, everything continues to work as
expected.

Also sanity-checked on i686 and x86_64 w/o any regressions (problem only
manifests on ia64, but patch is in common code).

Upstream
--------
Slightly different change (due to code drift) went in upstream a few
months ago:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b6e8f00fcd56b426371334d722d1f3fb251b7290

Please ACK

--
Jarod Wilson
jwilson@redhat.com

Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
---
 drivers/char/vt.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 4941c95..8bce52f 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -3301,9 +3301,6 @@ void do_blank_screen(int entering_gfx)
 		}
 		return;
 	}
-	if (blank_state != blank_normal_wait)
-		return;
-	blank_state = blank_off;
 
 	/* entering graphics mode? */
 	if (entering_gfx) {
@@ -3311,10 +3308,15 @@ void do_blank_screen(int entering_gfx)
 		save_screen(vc);
 		vc->vc_sw->con_blank(vc, -1, 1);
 		console_blanked = fg_console + 1;
+		blank_state = blank_off;
 		set_origin(vc);
 		return;
 	}
 
+	if (blank_state != blank_normal_wait)
+		return;
+	blank_state = blank_off;
+
 	/* don't blank graphics */
 	if (vc->vc_mode != KD_TEXT) {
 		console_blanked = fg_console + 1;
-- 
1.5.3.5.645.gbb47