[RFC] [Maverick] UBUNTU: SAUCE: pm: Config option to disable handling of console during suspend/resume

[Leann Ogasawara]

Hi Amit,

We've got a bug report [1] from Phillip (CC'd) that when resuming from
suspend on Maverick his display never comes back out of power save mode
with the latest 2.6.35 Maverick kernels.  He tested yesterday's 2.6.35
daily mainline build and could not reproduce the issue.  He was able to
narrow it down to the CONFIG_PM_DISABLE_CONSOLE option being enabled.
This config option originates from an Ubuntu SAUCE patch (inlined below)
which was authored by yourself a few years ago.  Is it still necessary
that we carry this patch?  I'm inclined to drop it, or at least disable
the config option, especially since it appears to be causing issues.
Your thoughts? 

Thanks,
Leann

[1] https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/594885

>From 6063b4dc3721a63d70f81522fa130372ded60b45 Mon Sep 17 00:00:00 2001
From: Amit Kucheria <amit.kucheria at ubuntu.com>
Date: Fri, 23 May 2008 11:43:45 +0300
Subject: [PATCH] UBUNTU: SAUCE: pm: Config option to disable handling of console during suspend/resume

Signed-off-by: Amit Kucheria <amit.kucheria at ubuntu.com>

Signed-off-by: Ben Collins <ben.collins at canonical.com>
---
 kernel/power/Kconfig   |   15 +++++++++++++++
 kernel/power/console.c |    4 ++++
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 5c36ea9..e829331 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -133,6 +133,21 @@ config SUSPEND_FREEZER
 config HIBERNATION_NVS
 	bool
 
+config PM_DISABLE_CONSOLE
+	bool "Disable Power Management messing with the active console"
+	depends on PM
+	default n
+	---help---
+	  By default, PM will take over the active console (generally, this means
+	  switching to the console when suspending from X). This can at times cause
+	  problems, especially if userspace suspend scripts try to do things with
+	  the console before or after suspending (e.g. calling vbestate).
+
+	  To work around this, enable this option so that PM will not handle the
+	  console.
+
+	  If unsure, say N.
+
 config HIBERNATION
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
diff --git a/kernel/power/console.c b/kernel/power/console.c
index 218e5af..5b254ba 100644
--- a/kernel/power/console.c
+++ b/kernel/power/console.c
@@ -17,19 +17,23 @@ static int orig_fgconsole, orig_kmsg;
 
 int pm_prepare_console(void)
 {
+#ifndef CONFIG_PM_DISABLE_CONSOLE
 	orig_fgconsole = vt_move_to_console(SUSPEND_CONSOLE, 1);
 	if (orig_fgconsole < 0)
 		return 1;
 
 	orig_kmsg = vt_kmsg_redirect(SUSPEND_CONSOLE);
+#endif
 	return 0;
 }
 
 void pm_restore_console(void)
 {
+#ifndef CONFIG_PM_DISABLE_CONSOLE
 	if (orig_fgconsole >= 0) {
 		vt_move_to_console(orig_fgconsole, 0);
 		vt_kmsg_redirect(orig_kmsg);
 	}
+#endif
 }
 #endif
-- 
1.7.0.4