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

[Benjamin Tissoires]

Hi,

On Tue, Dec 6, 2011 at 23:31, Baptiste Jonglez <baptiste at jonglez.org> wrote:
> On Tue, Dec 06, 2011 at 11:12:26PM +0100, Benjamin Tissoires wrote:
>> Hi Baptiste,
>
> Hi,
>
>> On Tue, Dec 6, 2011 at 22:51, Baptiste Jonglez <baptiste at jonglez.org> wrote:
>> > 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).
>
> No, with the patch, it worked out-of-the-box.

mmm, this is weird. We must not have the same bios or device version.
We need to explicitly set the LCD2 up.

>
> I can even control the brightness in
> `/sys/class/backlight/acpi_video0/brightness' (it affects both
> displays at the same time though). But even at 0, it's still perfectly
> readable.

Yes, the acpi can control both brightness. But WMI can control each
brightness. However, we are not sure this is what people want. So we
do not plan to introduce a second brightness control.

>
> Maybe this a bug that got fixed recently? I've actually tried the 3.1
> kernel (and then the 3.2-rc4) because I noticed a lot of commits and
> improvements in the i915 driver recently.

We doubled-checked on 3.2-rc4, and we still need our patch. This is
definitively a bios/hardware configuration problem.

Cheers,
Benjamin

>
>> > Thanks Benjamin!
>>
>> All the credits are from Ajax and somebody else on IRC I don't recall,
>> really sorry. Thanks to them.
>>
>> Cheers,
>> Benjamin.
>
> Regards,
> Baptiste