Re: drm2 regression: backlight adjustment on ivybridge no longer works

29.01.2015 12:46, Ranjan1018 . пишет:
> 2015-01-28 10:11 GMT+01:00 Adrian Chadd <adrian_at_freebsd.org>:
>
>> ugh, so because i can't sleep, I read the Linux i915 history for
>> backlight changes.
>>
>> Turns out if I disable bit 30 in ivb_pch_pwm_override() to register
>> BLC_PWM_PCH_CTL1, the acpi video setting works. The keyboard settings
>> still don't, but I'll worry about that later.
>>
>> Bit 30 in the linux drm code is:
>>
>> #define   BLM_PCH_OVERRIDE_ENABLE               (1 << 30)
>>
>> The linux dri code doesn't set that for ivybridge - only for broadwell.
>>
>> (also, the linux driver has POSTING_READ() which I'm guessing is to
>> ensure things made it out to the device and have been flushed before
>> doing another IO operation.)
>>
>> I have my (via sysctl) panel backlight control working again.
>>
>>
>>
>> -adrian
>>
> Thank you guys,
> the backlight control works again on my laptop with this patch, suggested
> by Adrian :
>
> --- sys/dev/drm2/i915/intel_display.c.orig   (revision 277487)
> +++ sys/dev/drm2/i915/intel_display.c        (working copy)
> _at__at_ -6995,7 +6995,7 _at__at_
>       */
>      I915_WRITE(BLC_PWM_CPU_CTL2, PWM_ENABLE);
>      I915_WRITE(BLC_PWM_CPU_CTL, 0);
> -    I915_WRITE(BLC_PWM_PCH_CTL1, PWM_ENABLE | (1<<30));
> +    I915_WRITE(BLC_PWM_PCH_CTL1, PWM_ENABLE);
>  }
>
>  void intel_modeset_init_hw(struct drm_device *dev)
>

This patch fixes problem for me too, but only when acpi_video module is
not loaded. With acpi_video loaded I still see this errors (but it's
probably another topic):

Jan 29 19:02:27 thinkpad kernel: ACPI Exception: AE_AML_PACKAGE_LIMIT,
Index (0x0000000FF) is beyond end of object (length 0x16)
(20140926/exoparg2-452)
Jan 29 19:02:27 thinkpad kernel: ACPI Error: Method parse/execution
failed [\_SB_.PCI0.LPCB.EC0_.BRNS] (Node 0xfffff80007541b00),
AE_AML_PACKAGE_LIMIT (20140926/psparse-552)
Jan 29 19:02:27 thinkpad kernel: ACPI Error: Method parse/execution
failed [\_SB_.PCI0.VID_.LCD0._BCM] (Node 0xfffff80007550280),
AE_AML_PACKAGE_LIMIT (20140926/psparse-552)
Jan 29 19:02:27 thinkpad kernel: can't evaluate
\_SB_.PCI0.VID_.LCD0._BCM - AE_AML_PACKAGE_LIMIT