suspend/resume on Lenovo X1 (regression from reports on wiki)

[Bengt Ahlgren]

Jung-uk Kim <jkim at FreeBSD.org> writes:

> On 2013-09-04 18:47:47 -0400, Jung-uk Kim wrote:
>> On 2013-09-04 18:39:07 -0400, Bengt Ahlgren wrote:
>>> The value of hw.acpi.video.lcd0.brightness changes when the
>>> screen brightness keys (Fn+Home/End) are pressed, but nothing
>>> happens with the screen.  Same goes for changing the value with
>>> sysctl.  After a fresh boot it works with one issue.  The screen
>>> brightness level seems to lag behind one keypress.  Without
>>> acpi_video, screen brightness changes without the lag.
>> 
>>> hw.acpi.video.lcd0.active is always stuck at 0 - can't change
>>> with sysctl (regardless if the screen is on after a fresh boot,
>>> or black after a text console suspend/resume):
>> 
>>> [root at bit ~]# sysctl hw.acpi.video.lcd0.active=1 
>>> hw.acpi.video.lcd0.active: 0 -> 0
>> 
>>> Again, for my old X40 with non-KMS Xorg intel driver has 
>>> (curiously, the screen blinks when issuing this sysctl command):
>> 
>>> [bengta at P142 ~]$ sysctl hw.acpi.video hw.acpi.video.lcd0.active:
>>> 1 hw.acpi.video.crt0.active: 0
>> 
>> Then, KMS probably breaks acpi_video(4), too. :-(
>
> kib let me know that there is a way to make it work but it was not
> well-integrated to i915kms.ko.  If you are interested in fixing it,
> dev/drm2/i915/intel_opregion.c is the source and you can download the
> specification from here:
>
> https://01.org/linuxgraphics/sites/default/files/documentation/acpi_igd_opregion_spec.pdf

Hmm, scanning that spec, I wonder whether the opregion functionality is
better placed together with acpi_video, and then i915kms makes calls to
that instead?  Hmm, again, perhaps the intel platform needs opregion
support to work properly also without the kms driver.  Could be an
explanation for the backlight issues.  (Just speculation so far...  I
have no idea if/how this relates to or interacts with options VESA)

Bengt