linux-kernel - Re: [PATCH] Platform: samsung-laptop: add DMI information for Samsung N150 Plus

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Message-ID: <CANq1E4Sxt7cnOBdP7ggBYjp-OVzub1nPOZ_PEnhOp242EEeNSg@mail.gmail.com>
Date:	Thu, 29 Dec 2011 15:02:30 +0100
From:	David Herrmann <dh.herrmann@...glemail.com>
To:	Corentin Chary <corentin.chary@...il.com>
Cc:	Richard Schütz <r.schtz@...nline.de>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Andrzej Prochyra <andrzej@...chyra.name>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Zhang, Rui" <rui.zhang@...el.com>
Subject: Re: [PATCH] Platform: samsung-laptop: add DMI information for Samsung
 N150 Plus

On Thu, Dec 29, 2011 at 12:49 PM, Corentin Chary
<corentin.chary@...il.com> wrote:
> On Thu, Dec 29, 2011 at 12:45 PM, Richard Schütz <r.schtz@...nline.de> wrote:
>> Am 29.12.2011 11:23, schrieb Corentin Chary:
>>>
>>> On 12/26/2011 11:22 AM, David Herrmann wrote:
>>>
>>>> On Mon, Dec 26, 2011 at 10:49 AM, Corentin Chary
>>>> <corentin.chary@...il.com> wrote:
>>>>>
>>>>> On Sat, Dec 24, 2011 at 3:28 PM, David Herrmann
>>>>> <dh.herrmann@...glemail.com> wrote:
>>>>>>
>>>>>> On Sat, Dec 24, 2011 at 3:20 PM, Matthew
>>>>>> Garrett<mjg59@...f.ucam.org> wrote:
>>>>>>>
>>>>>>> On Sat, Dec 24, 2011 at 02:12:57PM +0000, Andrzej Prochyra wrote:
>>>>>>>>
>>>>>>>> 'acpi_video0' not functional. Brightness can be controlled through
>>>>>>>> intel_backlight interface. There are 21 brightness levels and the
>>>>>>>> backlight can be turned off.
>>>>>>>
>>>>>>>
>>>>>>> If acpi_video0 doesn't work then we either need to work out why
>>>>>>> it's not
>>>>>>> working or make it vanish completely, so this patch isn't the correct
>>>>>>> approach.
>>>>>>
>>>>>>
>>>>>> Just to make clear, intel_backlight isn't working properly either. If
>>>>>> my laptop boots with backlight at 50% then intel_backlight will only
>>>>>> work in the range 0%-50% on my machine. If I use the samsung module to
>>>>>> set it to 100% then intel_backlight works correctly in the range
>>>>>> 0-100% until next reboot/suspend.
>>
>>
>> The same problem exists on my N145 Plus, too.
>>
>>>>>> So I'd recommend staying with the samsung module and disabling the
>>>>>> acpi_backlight entirely. The samsung module is the only backlight
>>>>>> control which works properly.
>>>>>
>>>>>
>>>>> Can I take a look at the DSDT to see how it's broken ?
>>>>> If it's really not functional, then it should be added to the
>>>>> blacklist in video_detect.c
>>>>
>>>>
>>>> Raw and disassembled dsdt is attached.
>>>
>>>
>>> Took a quick look but didn't find anything obvious. What happens exactly
>>> with acpi_video0 ?
>>
>>
>> Either Samsung's ACPI is totally broken [ACPI Warning: _BQC returned an
>> invalid level (20110623/video-472)] or they just don't support backlight
>> setting via ACPI at all. Therefore it's implemented in the SABI stuff. So
>> every device that needs SABI should be blacklisted in video_detect.
>
> And that's ? Because new laptops that use SABI seems to have a working
> acpi_video0.
> Currently, N1{4,5}* seems to be affected.

the acpi_video0 on my machine does nothing. The intel_backlight has
the described bug and the samsung SABI backlight needs the fix that
setting the backlight only works from/to 0 and 7 (this fix is already
upstream).

The SABI thing is working for me so I'd prefer it. I have a N210P
which is detected as: N150P/N210P/N220P

I hope that helps
Regards
David
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