[Dual-LVDS Acer Iconia laptop] i915/DRM issue: one screen stays off [3.2-rc4+]

[Benjamin Tissoires]

Hi Baptiste,

On Tue, Dec 6, 2011 at 22:51, Baptiste Jonglez <baptiste at jonglez.org> wrote:
> On Mon, Dec 05, 2011 at 11:00:41AM +0800, joeyli wrote:
>> Add Cc. to platform-driver-x86 and linux-acpi
>>
>> Hi Baptiste
>>
>> 於 日，2011-12-04 於 17:07 +0100，Baptiste Jonglez 提到：
>> > Hi,
>> >
>> > I've got a lot of troubles with a dual-LVDS Acer laptop (it doesn't
>> > have a keyboard, but two displays with touchscreens)
>> >
>> > The Intel GPU is integrated into the Core i5-480M CPU: it's a bit
>> > older than Sandybridge, as it seems to be based on the Arrandale
>> > micro-architecture.
>> >
>> > In the BIOS, both displays work fine; but as soon as the kernel boots
>> > up, the second display (i.e. the one where you usually find a
>> > keyboard) is turned off. The main display works as expected.
>> >
>> > xrandr reports two LVDS displays: LVDS1, which is connected, and
>> > LVDS2, which is marked as "disconnected". No matter what I tried, I
>> > can't bring that second display up.
>> >
>> > During the boot, just after the drm is set up, the following message
>> > shows up:
>> >
>> >   [drm:intel_dsm_pci_probe] *ERROR* failed to get supported _DSM functions
>> >
>> > (attached is the relevant part of dmesg [1])
>
> The second screen works fine with the attached patch. It actually is
> 6 months old but seems to have been lost in the wild...

You don't have the problem of the second backlight still off?
On our Iconia, we need to trigger a special DMI command to set it up
(SDSS, IIRC).

>
> Thanks Benjamin!

All the credits are from Ajax and somebody else on IRC I don't recall,
really sorry. Thanks to them.

Cheers,
Benjamin.

>
> There is still the issue of unhandled acer-wmi events, but it's far
> less incapacitating. I wonder what's the best way to report events to
> userspace, though (e.g. for the "keyboard" button, userspace might
> want to know when it is pressed in order to display a virtual keyboard
> or any other fancy stuff)
>
> Joey, if you need more logs for acer-wmi, I'll be happy to provide.
>
>
> Baptiste