linux-kernel - Re: [PATCH 2/2] ACPI / video / i915: Remove ACPI backlight if firmware expects Windows 8

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Date:	Tue, 10 Sep 2013 13:42:13 +0800
From:	Aaron Lu <aaron.lu@...el.com>
To:	Igor Gnatenko <i.gnatenko.brain@...il.com>
CC:	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Matthew Garrett <matthew.garrett@...ula.com>,
	Seth Forshee <seth.forshee@...onical.com>,
	"Lee, Chun-Yi" <joeyli.kernel@...il.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Len Brown <lenb@...nel.org>,
	Yves-Alexis Perez <corsac@...ian.org>,
	Felipe Contreras <felipe.contreras@...il.com>,
	Lee Chun-Yi <jlee@...ell.com>,
	Henrique de Moraes Holschuh <hmh@....eng.br>
Subject: Re: [PATCH 2/2] ACPI / video / i915: Remove ACPI backlight if firmware
 expects Windows 8

On 09/10/2013 01:22 PM, Igor Gnatenko wrote:
> On Tue, 2013-09-10 at 13:16 +0800, Aaron Lu wrote:
>> On 09/10/2013 01:13 PM, Igor Gnatenko wrote:
>>> On Tue, 2013-09-10 at 11:27 +0800, Aaron Lu wrote:
>>>> On 09/09/2013 07:44 PM, Igor Gnatenko wrote:
>>>>> On Mon, 2013-09-09 at 16:42 +0800, Aaron Lu wrote:
>>>>>> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
>>>>>> index f466980..75fba17 100644
>>>>>> --- a/drivers/gpu/drm/i915/i915_dma.c
>>>>>> +++ b/drivers/gpu/drm/i915/i915_dma.c
>>>>>> @@ -1650,7 +1650,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>>>>>>  	if (INTEL_INFO(dev)->num_pipes) {
>>>>>>  		/* Must be done after probing outputs */
>>>>>>  		intel_opregion_init(dev);
>>>>>> -		acpi_video_register();
>>>>>> +		__acpi_video_register(i915_take_over_backlight);
>>>>>>  	}
>>>>>>  
>>>>>>  	if (IS_GEN5(dev))
>>>>>
>>>>> I can't compile:
>>>>>
>>>>>
>>>>> DEBUG: drivers/gpu/drm/i915/i915_dma.c: In function 'i915_driver_load':
>>>>> DEBUG: drivers/gpu/drm/i915/i915_dma.c:1661:3: error: implicit
>>>>> declaration of function
>>>>> '__acpi_video_register' [-Werror=implicit-function-declaration]
>>>>> DEBUG:    __acpi_video_register(i915_take_over_backlight);
>>>>> DEBUG:    ^
>>>>> DEBUG: cc1: some warnings being treated as errors
>>>>> DEBUG: make[4]: *** [drivers/gpu/drm/i915/i915_dma.o] Error 1
>>>>> DEBUG: make[3]: *** [drivers/gpu/drm/i915] Error 2
>>>>> DEBUG: make[2]: *** [drivers/gpu/drm] Error 2
>>>>> DEBUG: make[1]: *** [drivers/gpu] Error 2
>>>>> DEBUG: make: *** [drivers] Error 2
>>>>>
>>>>
>>>> The two patches are based on top of Rafael's linux-next tree. I just
>>>> tried it again, no compile problem for me. I also tried on today Linus'
>>>> master tree, as there are some updates from i915, two conflicts exist.
>>>> I've just resolved them and will update it in next revision.
>>>> If you want to try it now, please use:
>>>> https://github.com/aaronlu/linux acpi_video_rework
>>>>
>>>> Thanks,
>>>> Aaron
>>>
>>> Thanks. this patch fixes my problems w/ compilation. I've tested this
>>> two patches and after apply I have:
>>> $ tree /sys/class/backlight/
>>> /sys/class/backlight/
>>> |-- acpi_video0
>>> -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
>>> `-- intel_backlight
>>> -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight
>>>
>>> 2 directories, 0 files
>>>
>>> I think it's didn't unregistered.. I may forget. I need to apply one of
>>> patch from Matthew ?
>>
>> You need to specify i915.take_over_backlight=1 in kernel cmdline, that
>> module option is set to false by default for now.
>>
>> Thanks for the test.
>>
>> -Aaron
>>
>>>
>>> Some strings from logs:
>>> DMI: LENOVO 23205NG/23205NG, BIOS G2ET92WW (2.52 ) 02/22/2013
>>> thinkpad_acpi: Standard ACPI backlight interface available, not loading
>>> native one
>>>
>>
> 
> Thanks for quick answer. Yes. This option do unregister. Thanks. but for
> this patch-set I also need "[PATCH 2/3] ACPI / video: Always call
> acpi_video_init_brightness() on init" from Matthew (for notifications in
> DE).

That patch is reverted as it cause problem for other system:
https://bugs.freedesktop.org/show_bug.cgi?id=68355

OTOH, the thinkpad-acpi module already has a call to _BCL except that
the tpacpi_acpi_handle_locate failed to locate video controller's handle:
https://bugzilla.kernel.org/show_bug.cgi?id=51231#c121
I'll see if I can figure out why.

Thanks,
Aaron
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