On Wed, 2007-09-12 at 18:00 +0200, Maik Broemme wrote:
> Hi,
>
> Maik Broemme <mbroemme@xxxxxxxxxxxxx> wrote:
> > Hi,
> >
> > Maik Broemme <mbroemme@xxxxxxxxxxxxx> wrote:
> > > Hi,
> > >
> > > i have a couple of small questions. :) I own an IBM ThinkPad X40 and a
> > > Lenovo ThinkPad X61 Tablet and just hacked somewhere around in the
> > > 'thinkpad-acpi-0.16-20070904' sources.
> > >
> > > I started my work on adding support for the brightness setup which has
> > > 16 level on the newer X61/X61s and X61 Tablet laptops. Well my problem
> > > is (or i am to stupid to understand) that setting the brightness level
> > > with TP_CMOS_BRIGHTNESS_UP did not set it until level 16. Is this a
> > > limitation of the thinkpad-acpi itself or somewhere inside the NVRAM?
> > >
> > > As notice: With brightness mode 1 (which reads data from EC via
> > > acpi_ec_read) the setting of any brightness level is not working.
> > >
> > > Maybe someone can give me a hint where i can start to track this issue
> > > and how to solve it. :)
> > >
> >
> > okay some other information, i am still able to set at least 15 of the
> > 16 levels via '/proc/acpi/video/VID/LCD0/brightness' It shows:
> >
> > root@bart:~# cat /proc/acpi/video/VID/LCD0/brightness
> > levels: 100 100 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 100
> > current: 90
> >
> > If i count all values (and the 100 only one time) it are 16 levels.
> > Well the level 100 i can not set (kernel is stock 2.6.22.6) Well this
> > looks like an ACPI bug for me, or a broken firmware. If do the
> > following:
> >
> > root@bart:~# for i in 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 ; do sleep 1s ; echo "${i}" > /proc/acpi/video/VID/LCD0/brightness ; done
> >
> > i can set at least 15 brightness level. I think the best solution would
> > be to use the ACPI video driver to set the brightness, did anyone agree
> > or disagree? :)
> >
> > If i am correct thinkpad-acpi should trac the keypress event and then
> > trigger some acpi function to set the brightness level.
> >
>
> Sorry a last thing which should be mentioned. :) The ACPI video driver
> correctly updates the CMOS NVRAM, but thinkpad-acpi can only handle
> values until acpi-video value 55, for example:
>
> root@bart:~# echo 20 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 0
> root@bart:~# echo 25 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 1
> root@bart:~# echo 30 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 2
> root@bart:~# echo 35 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 3
> root@bart:~# echo 40 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 4
> root@bart:~# echo 45 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 5
> root@bart:~# echo 50 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 6
> root@bart:~# echo 55 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 7
> root@bart:~# echo 60 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 0
> root@bart:~# echo 65 > /proc/acpi/video/VID/LCD0/brightness
> root@bart:~# cat /proc/acpi/ibm/brightness | grep level:
> level: 1
But brightness is set correctly (not the value but the background
brightness itself)?
This is a thinkpad_acpi bug and the fact that it can only cope with 8
brightness levels.
I have two ideas on how the thinkpad_acpi driver could handle these
machines:
- set brightness levels from current up to max (until it does not
change anymore) -> disadvantage: unspecified values are written
and a SMI with a undefined value will be fired (e.g. a value of
8 for < X61/T61 and a value of 16 for X61/T61...)
- Use dmi decode again and set max brightness levels to 0-15 in
X61/T61/.. case.
Both are really ugly workarounds and should only be added if there is no
time for doing it right for the next bigger kernel release.
Doing it right is IMO, ripping out brightness control for *Lenovo*
ThinkPads only and let the video module do brightness control instead.
This should also be done for the video ThinkPad extensions or the
ThinkPad video extensions might interfere with the video driver.
Thomas
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