i915 backlight

[Aaron Lu]

On 08/01/2013 12:36 AM, Borislav Petkov wrote:
> On Wed, Jul 31, 2013 at 06:22:52PM +0200, Borislav Petkov wrote:
>> Dudes,
>>
>> has anyone already reported this (happens on Linus of today +
>> tip/master):
> 
> Oh, one more thing: I can't control the backlight anymore on this x230
> with the Fn-Fx keys and this is most probably related to that recent
> backlight revert story. If there is a new approach I can test, please
> let me know.

Can you please run acpi_listen and then press the Fn-Fx key, see if the
events are correctly sent out?

> 
> Btw, it worked before on this machine with "acpi_backlight=vendor" on
> the cmdline.

>From the bug page:
https://bugzilla.kernel.org/show_bug.cgi?id=51231#c80
I got the impression that both the acpi_video interface and the vendor
interface thinkpad_screen are broken. So adding this cmdline here works
suggests that either thinkpad_screen works or thinkpad vendor driver
doesn't get loaded or doesn't create that interface for some reason.

Alternatively, if the intel_backlight interface works(highly possible),
you can use xorg.conf to specify the that backlight interface for X.

Section "Device"
        Option     "Backlight"	"intel_backlight"
	Identifier  "Card0"
	Driver      "intel"
	BusID       "PCI:0:2:0"
EndSection

Thanks,
Aaron