Re: [PATCH] Platform: samsung-laptop: add DMI information for SamsungN150 Plus

From: David Herrmann
Date: Thu Dec 29 2011 - 09:02:33 EST

On Thu, Dec 29, 2011 at 12:49 PM, Corentin Chary
<corentin.chary@xxxxxxxxx> wrote:
> On Thu, Dec 29, 2011 at 12:45 PM, Richard Schütz <r.schtz@xxxxxxxxxxx> 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@xxxxxxxxx> wrote:
>>>>> On Sat, Dec 24, 2011 at 3:28 PM, David Herrmann
>>>>> <dh.herrmann@xxxxxxxxxxxxxx> wrote:
>>>>>> On Sat, Dec 24, 2011 at 3:20 PM, Matthew
>>>>>> Garrett<mjg59@xxxxxxxxxxxxx> 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

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
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at