On Mon, 14.10.13 10:36, Aaron Lu (aaron.lu@xxxxxxxxx) wrote:
> > - Backlight control doesn't work via ACPI without acpi_osi="!Windows 2012"
> > - Backlight control doesn't work via ACPI with acpi_osi="!Windows 2012"
> > - Backlight control doesn't work via EC commands from ideapad-laptop.c
> >
> > The only way backlight handling is supported on the Yoga 13 is via the
> > intel video driver.
>
> Since I don't have access to the acpidump of this system, my only
> question is, does the firmware has a _OSI("Windows 2012") query in DSDT
> table?
Yes, it appears to do that as part of _OSC.
The disassembled DSDT table is here:
http://0pointer.de/public/yoga13-dsdt.dsl
> > Or in other words: the situation for the Yoga 13 is *unrelated* to the
> > Windows 8 issues, and your patch.
>
> I think they are related...
> If the firmware is compatible to Windows 8, then my patch will disable
> ACPI video backlight interface to prefer GPU's interface.
OK, that might indeed work.
> > I'll soon send another patch which also blacklists the thing in the
> > ideapad driver, so that only the intel backlight driver is enabled on
> > Yoga 13 systems, at which point everything will work fine.
>
> Right, that is needed. And if going with my patch, the ideapad driver
> will need to be patched similarly like thinkpad_acpi to add a check of
> acpi_video_backlight_support before it decides to register its own
> backlight interface.
The ideapad driver currently skips registration of the backlight device
if acpi_video_backlight_support() returns true. is that all you need?
Hmm, regarding your patch series, do you plan to skip the registration
of the acpi backlight device if the "raw" device is supported? I mean,
the intel driver could be compiled as a module (and generally is on the
popular distros), so at the time the ACPI subsystem wants to register
the backlight device and know if a raw backlight device is around it
never will be, so what is the point of that? Or am I missing something?
Lennart
--
Lennart Poettering - Red Hat, Inc.
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