mactel-support-community team mailing list archive

[Seth Forshee <seth.forshee@xxxxxxxxxxxxx>]

On Tue, Jan 31, 2012 at 09:27:12AM -0800, Colin D Bennett wrote:
> Hi Seth,
> 
> On Tue, 31 Jan 2012 10:55:34 -0600
> Seth Forshee <seth.forshee@xxxxxxxxxxxxx> wrote:
> 
> > [Note that I'm not subscribed to the mactel-support-community
> > list; please Cc me on any replies]
> 
> Noted.
> 
> > Hi all,
> > 
> > I've been doing some work on the Apple backlight driver in the
> > Linux kernel to get support for adjusting the screen brightness
> > via the gmux device. This will hopefully get working screen
> > brightness adjustment for all Macs that that don't currently have
> > it. This support has been floating around in various forms for a
> > while now, and what I'm trying to do is get it into stock Ubuntu
> > so brightness adjustment will work out-of-the box, more or less.
> > 
> > The driver changes are pretty much complete, and now I'd like to
> > get testing on as many different Apple models as possible. If
> > you've got a machine with a built-in dispaly and would be willing
> > to test, please visit the following page for instructions on how
> > you can help.
> 
> I updated the wiki page with results from my MacBookPro5,1.
> My backlight was working before, with stock Oneiric system, so I am
> testing just to make sure the new driver *still* works.

Thanks, Colin! I want testing for both machines that do and don't have
working backlights currently, so this is very helpful.

> Note that I have no acpi_video device, although the wiki page says
> I should have it at a minimum:
> 
>     $ ls /sys/class/backlight
>     gmux_backlight

Hmm. If that's the only device you have then I don't understand how you
could have had working brightness adjustments previously. What devices
are present if you uninstall the test driver?

Also, you aren't booting with acpi_backlight=vendor, are you? If you are
it will show up in /proc/cmdline.

>     cdb@svelte:/sys/class/backlight/gmux_backlight$ ls -l
>     total 0
>     -r--r--r-- 1 root root 4096 2012-01-31 09:16 actual_brightness
>     -rw-r--r-- 1 root root 4096 2012-01-31 09:16 bl_power
>     -rw-r--r-- 1 root root 4096 2012-01-31 09:17 brightness
>     lrwxrwxrwx 1 root root    0 2012-01-31 09:16 device -> ../../../00:08
>     -r--r--r-- 1 root root 4096 2012-01-31 09:16 max_brightness
>     drwxr-xr-x 2 root root    0 2012-01-31 09:16 power
>     lrwxrwxrwx 1 root root    0 2012-01-31 09:16 subsystem -> ../../../../../class/backlight
>     -r--r--r-- 1 root root 4096 2012-01-31 09:16 type
>     -rw-r--r-- 1 root root 4096 2012-01-31 09:16 uevent
>     cdb@svelte:/sys/class/backlight/gmux_backlight$ cat max_brightness 
>     77978
> 
> Backlight adjustment through this gmux_backlight 'brightness' file
> works.  My backlight keys on the keyboard don't work, however, so I
> assume other changes are required to hook that up to the new
> backlight driver.

This is for the display backlight only. The keyboard backlight is a
completely different driver.

Thanks,
Seth