acpi_video_flags Reset on Resume-From-RAM

["Leo L. Schwab" <ewhac@best.com>]

	Suspend-to-RAM used to (mostly) work on this machine, but there
seems to have been a regression between 2.6.22.1 and 2.6.22.5.

	I have a ThinkPad Z61t, with an Intel Core 2 Duo and Intel 945GM
graphics.  My kernel command line contains the argument,
"acpi_sleep=s3_bios,s3_mode", which is the same as setting
/proc/sys/kernel/acpi_video_flags to 3.  This setting is suggested by
ThinkWiki.org for getting the Intel graphics to recover properly after
suspend-to-RAM.

	Under 2.6.22.1, this arrangement worked fine.  However, since I
upgraded the kernel to 2.6.22.5, the text console refuses to come back.
When I inspect acpi_video_flags, the value has been reset to zero.

	Sequence:
	- Boot system.
	- Inspect /proc/sys/kernel/acpi_video_flags -- it contains 3.
	- Trigger suspend-to-RAM (done via 'hibernate-ram').  I have
	  configured 'hibernate' to leave acpi_video_flags alone.
	- Resume system.  Text console does not come back.  I can force X to
	  recover the display by pressing CTRL-ALT-F1 (switch to console)
	  followed by ALT-F7 (switch to X).
	- Inspect /proc/sys/kernel/acpi_video_flags -- it contains 0.
	- Force acpi_video_flags back to 3:
	  echo 3 > /proc/sys/kernel/acpi_video_flags
	- Inspect /proc/sys/kernel/acpi_video_flags -- it contains 3.
	- Trigger suspend-to-RAM.
	- Resume system.  Text console does not come back.  acpi_video_flags
	  contains zero again.

	I'm running a custom-compiled kernel (config available upon
request).  The highlights are SMP, PREEMPT, and NOHZ.

	Note that nothing short of a full reboot will restore the console.
Switching to a virtual console results in a blank screen.  Switching back to
X so far always works.  Since the console's busted, it's not immediately
clear how I might diagnose this further.  Suggestions?

					Schwab