[ltp] X61 Brightness Question

[Henrique de Moraes Holschuh]

On Wed, 15 Aug 2007, Hendrik-Jan Heins wrote:
> I just now redid everything with 0.15.
> Unfortunatly, I see no difference in effects, except for the fact that
> I now NEED the video module to get brightness working

Eh?  It shouldn't have made any difference on that regard.  Are you sure
thinkpad-acpi was the only thing that changed?

> > The new thinkpads are moving to generic ACPI video handling, and that's the
> > ACPI video driver's business.
> Yup, I'm seeing that now.

You were doing so before...

> The brightness_mode=2 option doesn't seem to do much. I tried it with
> and without, but I saw no difference.

If you leave it out but start the driver with the debug=0xffff parameter,
you'll see it selects brightness_mode=2 for you.  The old way might or might
not work well on your thinkpad, it was removed because it was changing an EC
register that was not used anymore, so we better not touch it.

And it certainly wouldn't work right when reading brightness if you used
anything but thinkpad-acpi to change it.

> Actually now I do see 0-7 brightness levels in
> /sys/class/backlight/thinkpad_screen/actual_brightness
> Shouldn't I see more levels?

Yes, but I didn't figure out how to detect a 16-level thinkpad yet from the
ACPI tables.

> The scripts I'm using to set brightness:
...

You just did in userspace what the acpi video module does in kernel space,
but using thinkpad-acpi instead of the generic ACPI backlight level methods
to change the brightness.

That's why it was working before :p

-- 
  "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