[ltp] X200 brightness keys behavior weirdness - down is up, up is down (sometimes)

[Henrique de Moraes Holschuh]

On Wed, 29 Oct 2008, John Li wrote:
> On Tue, Oct 28, 2008 at 10:18:33AM -0200, Henrique de Moraes Holschuh wrote:
> > On Mon, 27 Oct 2008, John Li wrote:
> > > [    6.917378] thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
> > > [    6.917449] thinkpad_acpi: Disabling thinkpad-acpi brightness events by default...
> > > [    6.925138] thinkpad_acpi: Lenovo BIOS switched to ACPI backlight control mode
> > > [    6.925138] thinkpad_acpi: standard ACPI backlight interface available, not loading native one...
> > 
> > It is doing the right thing.  You now need a very new X.org, a very new
> > kernel (for a very new ACPI video, and various EC interrupt fixes)...
> 
> How new? I tend stick with the Debian kernels because I've had bad
> luck with compiling my own kernels (I unknowingly disable required
> options or modules and not being able to boot X, or something).

Much newer than that :(  2.6.28-rc with X.org from git.  It is likely that
you'd be much better off waiting for two or three months on this one.

For workarounds, you can *try* to not load ACPI video, and force
thinkpad-acpi to make the brightness control interface available (in CMOS
mode if it doesn't detect that automatically, which I believe it should).
Use the thinkpad-acpi from ibm-acpi.sf.net, otherwise you WILL get very
annoying delays on brightness key processing.

The X200 is engineered to work with ACPI video, so you will likely have to
enable the brightness keys in thinkpad-acpi as well, and either get HAL or
gnome or an acpid script to handle those.   This is exactly the WRONG thing
to do on most thinkpads, but it is the way to deal with the X61, X300 and
X200 *WHEN* working around the lack of Intel opRegion X.org support for
brightness change in a distro.

It *will* break horribly when X.org and the kernel start doing opRegion
control, BTW.

> And I've never tried building X.org before.

For this case, I think you better not try.  You'd be switching from somewhat
stable DRM to GEM-based bleeding-edge direct rendering which is fairly
likely to have annoying bugs both in X.org AND the kernel.

> I think they're okay. Though, the fan revs up much more often than
> under Vista, and it doesn't seem to slow down again, but that's
> another issue :).

Can you try to identify the situation when the thinkpad issues those events?
That way, we could add support for them... might be a powersave hint or
somesuch, Lenovo has been adding some of these lately...

> > > just work. Based on the dmesg output above, I assume they're handled
> > > by the standard ACPI backlight interface, and not thinkpad_acpi.
> > 
> > Correct.  And ACPI should just be telling the X.org driver what to do, but
> > X.org had a LOT of HIDEOUS bugs on that area (and ACPI video took some time
> > to be cleaned up as well, and had its bad share of bugs).
> 
> Good to know it's getting better :).

Oh, it is.  For Intel and ATi anyway.  Everything else seems to be eigher
ignored (maybe they don't need extra support? who knows) or in the dark
ages.

-- 
  "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