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

From: Richard Schütz
Date: Thu Dec 29 2011 - 06:46:30 EST

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

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.

Richard Schütz
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