Re: [Acpi4asus-user] 1005PE's and backlight controls

[Chris Bagwell <chris@cnpbagwell.com>]

On Wed, Apr 14, 2010 at 8:45 AM, Corentin Chary
<corentin.chary@gmail.com> wrote:
> On Wed, Apr 14, 2010 at 3:24 PM, Chris Bagwell <chris@cnpbagwell.com> wrote:
>> On Wed, Apr 14, 2010 at 1:16 AM, Corentin Chary
>> <corentin.chary@gmail.com> wrote:
>>> On Wed, Apr 14, 2010 at 4:34 AM, Chris Bagwell <chris@cnpbagwell.com> wrote:
>>>> Hi all,
>>>>
>>>> I've seen the following issue reported on various web pages but not sure if
>>>> it was directly reported.  First up, you guys know about issue with acpi_osi
>>>> of "Windows 2009" disables eeepc_backend and thats were eeepc_wmi comes in.
>>>>
>>>> There is a secondary bug though if you boot with acpi_osi="!Windows 2009"
>>>> (or "Linux").  The ACPI driver will take control of backlight controls with
>>>> Fn-F5/F6.  Those keys will work but has issues with Gnome and other user
>>>> processes.
>>>>
>>>> Anything that uses any of the /sys/* interfaces to control backlight do not
>>>> work correctly.  When software cycles threw levels, the behavior is kinda
>>>> odd.  It will cycle each time you dim to something like
>>>> Bright->Dim->Bight->Off->Bright->etc.  Also, Gnome will give no feedback
>>>> because eeepc_laptop discards the events and it will not make it to
>>>> /dev/input/event*.  And last, the status of current brightness is never
>>>> updated under /sys/* correctly which confuses Gnome as well.
>>>>
>>>> The secondary work around is to add acpi_backlight=vendor to boot options.
>>>> Then eepc_backlight takes charge and life is good.  Gnome gives visual
>>>> feedback and dimmer works as expected.
>>>>
>>>> Baring a firmware fix from Asus, would it be possible to enable some sort of
>>>> backlist for using ACPI backlight support and have 1005P's use eeepc_laptop?
>>>>
>>>> Chris
>>>
>>> Hi,
>>> Did you try the eeepc-wmi ? It's the long term solution and it don't need
>>> any extra kernel parameters. Yong Wang just added backlight support to it.
>>>
>>> http://git.kernel.org/?p=linux/kernel/git/mjg59/platform-drivers-x86.git;a=shortlog;h=refs/heads/for_linus
>>>
>>
>> I havent't tried it yet but it looks like it has same issue that
>> eeepc-laptop does.  If ACPI reports it handles backlight then
>> eeepc-wmi disables controlling of backlight and I'd get buggy ACPI
>> version.
>>
>> Does Yong happen to be on this email list?
>
> I don't think, but he reads platform-x86 which is now CCed
>
> Are you sure that the backlight behavior is the same with and without
> acpi_osi=Linux ?
>

I just retested to be sure and I think this confirms my suspicion that
using eeepc-wmi will not work either for 1005PE's backlights.

I tried no acpi_osi (same as "WIndows 2009" I guess),
acpi_osi="!Windows 2009", and acpi_osi="Linux"... all without
specifying acpi_backlight=vendor.  They all had the same behaviour.
The later two options allow eeepc-laptop to load and it always gives
message about ACPI controlling backlight.

You can see bad behaviour easiest by using Gnome's Preferences->Power
Management and controlling dimmer.  Sliding between 0% and 100% gives
seemingly random behaviour.  Anything software based acts bad.

Since ACPI did seem to be controlling backlight when I didn't specify
an acpi_osi, I suspect that means eeepc-wmi's logic to disable
backlight support would be invoked for 1005PE's.

Chris
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