[ltp] Re: [ibm-acpi-devel] thinkpad-acpi release 0.17-20071002 uploaded to ibm-acpi.sf.net

[Chris Hanson]

Henrique de Moraes Holschuh wrote:
> This release needs testing, and it needs testing FAST.  It has two important
> features that could make it for 2.6.24, if I get reports of how well they
> work in less than a week.
> 
> * Support for 16-level brightness for Lenovo thinkpads
>   (X61, T61 *needs* this.  X60 likely does so, as well.  T60 appears not to,
>    but I welcome tests, it should auto-detect).

This support works fine on my T60.  But I noticed a small problem: I tried

  echo 15 > /sys/class/backlight/thinkpad_screen/brightness

which generated EINVAL, as expected.  But afterwards all values
generated EINVAL, even reasonable ones such as 0 through 7.  EINVAL was
also generated when trying to set the value through procfs, either by
up/down or level N.  Prior to trying 15, the 0-7 values didn't signal
EINVAL errors.

The kern.log is filled with messages like

  Oct  3 00:21:50 ravna kernel: set_level status: 0

which originate in "drivers/acpi/video.c".  My interpretation is that
some variable in ACPI got set to a bad value and is now stuck there.