[ltp] Hotkeys not working after suspend/resume to disk (X220t)

[Henrique de Moraes Holschuh]

On Sat, 13 Aug 2011, Milan Plžík wrote:
>   I'm tring to configure X220 tablet to use suspend to disk, however
> it looks like after having successfully resumed, thinkpad hotkeys
> don't work. I tried to rmmod/modprobe thinkpad-acpi module, but with
> no luck. Interestingly, looks like suspend/resume to RAM fixes this
> issue -- hotkeys I tested started to work correctly again. I was not
> able to make further progress with debugging, but maybe some part of
> hotkeys_resume (drivers/platform/x86/thinkpad_acpi.c) disables hotkeys
> when resuming from disk; but I have not tested it.If there is anything
> I can do/test, I'm ready for any suggestions.

It could be a driver bug, yes.  But in that case, unloading it and
loading it back would fix the issue.

If it is indeed a problem in the driver, it will likely be caused by
something _new_ we should be doing to enable/disable something in the
X220 firmware that does not appreciate a suspend to disk.

I suggest you try switch suspend to disk to use ACPI S4 instead of S5.
That might cure the problem.  *KEEP TRACK OF POWER USAGE* when you do
so, you might find out that something in the thinkpad was not powered
off properly by S4.

IMO, suspend-to-disk is always a bad idea in Linux.  The way it reloads
the kernel in x86/x86_64 is not even close to safe re. firmware
interaction.

It is far safer to use only suspend-to-ram for always-available
situations, and power off in all others.

In any case, please report the issue in bugzilla.kernel.org.  We want to
fix it.  Also, please check whether a firmware update solves the issue.
If it does, PLEASE tell be about it and I will make sure to have the
driver complain to the user when it finds the problematic version of the
firmware.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh