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Old 02-22-10, 04:43 AM   #37
Julian2010
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Join Date: Feb 2010
Posts: 3
Default Re: Linux backlight driver

Hello everyone!

I think I have the same backlight control problem with my SAMSUNG Netbook: N510-KA04FR.
I installed (from CD) Ubuntu 9.10, updated now to kernel version 2.6.31-19.Gnome environment is used.
NVIDIA driver version is 195.36.03.
No nvbacklight driver is installed.
Everything works fine..except I can't control backlight level.
On this netbook, this is (should be..) done through the Fn/UP and Fn/Down keys.
At the beginning many Fn/Fx and the Fn/UP&DOWN keys were not at all recognized.
Now they are all recognized, assigned to the functions they should perform, the "key_non-release_event" issue of these keys has also been fixed.
So all the Fn/Fx work nicely and do what they should do, but not the Fn/UP&DOWN who have still no effective action on the actual screen backlight level.

For the action of Fn/UP&DOWN , the observed facts are:
1-Fn/UP &Fn/DOWN change the backlight level only when still on the Grub page.
2- Once booted and logged, action on Fn/UP or Fn/DOWN do let appear on screen the black "brightness bubble" with its brightness level index.This index is changed accordingly to the Fn/UP or Fn/DOWN action.No change on actual backlight level.
3- The content of system file /proc/acpi/video/IGPU/LCD0/brightness is actually modified by the action on Fn/Up &Fn/DOWN keys: its content reads
"levels: 20 30 40 50 60 70 80 100
current: xx"
,meaning the value of xx is increased/decreased according to the authorized levels.
4- The file /sys/class/backlight/acpi_video0 contains , among other subfolders, «*actual_brightness*», «*brightness*» , «max_brightness*» and «*bl_power*»
The contents of «*actual_brightness*» and «*brightness*» are the same and changed when using the Fn/UP or Fn/DOWN keys: from 0 (when brightness bubble shows a zero value index) to 7 (when brightness bubble shows a maximum value index).
The «*bl_power*» content seems to be always 0.
5- The brightness steps in /proc/acpi/video/IGPU/LCD0/brightness and in /sys/class/backlight/acpi_video0/actual_brightness & brightness sub-folders match together, although the numerical value themselves differ: «*20*» matches «*0*» , and «*100*» matches «*7*» for example.
6-Via terminal command, the content of /proc/acpi/video/IGPU/LCD0/brightness can be echoed and changed, also without action on actual backlight level.
7- Terminal command xbacklight answers: "No outputs have backlight property"

First questions are related to the identification of the problem itself:
From what is described hereabove, does the N510 face the same backlight control problem that is described with some Sony laptops?
What should I try/test additionnally to make sure it is (or it is not) the same problem if there is any doubt?

Then,if the problem is the same, what should be done to modify the "sony_laptop_ solution" provided by guillaumezin so that it could work on a SAMSUNG N510 netbook?
Please note I am not able to do myself such alterations, as I am quite new to the Linuxian world..

Additional informations about this netbook:

answer to cat /sys/class/dmi/id/sys_vendor:
SAMSUNG ELECTRONICS CO., LTD. (with a space between «*CO.,*» and «*LTD.*»

Answer to cat/sys/class/dmi/id/product-name:
N510

output of lspci -nn:
xxxx@MonNetbook:~$ lspci -nn
00:00.0 Host bridge [0600]: nVidia Corporation MCP79 Host Bridge [10de:0a82] (rev b1)
00:00.1 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0a88] (rev b1)
00:03.0 ISA bridge [0601]: nVidia Corporation MCP79 LPC Bridge [10de:0aae] (rev b3)
00:03.1 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0aa4] (rev b1)
00:03.2 SMBus [0c05]: nVidia Corporation MCP79 SMBus [10de:0aa2] (rev b1)
00:03.3 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0a89] (rev b1)
00:03.5 Co-processor [0b40]: nVidia Corporation MCP79 Co-processor [10de:0aa3] (rev b1)
00:04.0 USB Controller [0c03]: nVidia Corporation MCP79 OHCI USB 1.1 Controller [10de:0aa5] (rev b1)
00:04.1 USB Controller [0c03]: nVidia Corporation MCP79 EHCI USB 2.0 Controller [10de:0aa6] (rev b1)
00:06.0 USB Controller [0c03]: nVidia Corporation MCP79 OHCI USB 1.1 Controller [10de:0aa7] (rev b1)
00:06.1 USB Controller [0c03]: nVidia Corporation MCP79 EHCI USB 2.0 Controller [10de:0aa9] (rev b1)
00:08.0 Audio device [0403]: nVidia Corporation MCP79 High Definition Audio [10de:0ac0] (rev b1)
00:09.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Bridge [10de:0aab] (rev b1)
00:0b.0 IDE interface [0101]: nVidia Corporation MCP79 SATA Controller [10de:0ab5] (rev b1)
00:10.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0aa0] (rev b1)
00:15.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0ac6] (rev b1)
00:16.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0ac7] (rev b1)
00:17.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0ac7] (rev b1)
02:00.0 VGA compatible controller [0300]: nVidia Corporation C79 [Quadro FX 470M] [10de:087f] (rev b1)
03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:8192] (rev 01)
04:00.0 Ethernet controller [0200]: Marvell Technology Group Ltd. 88E8040 PCI-E Fast Ethernet Controller [11ab:4354] (rev 13)
xxxx@MonNetbook:~$

Last edited by Julian2010; 02-22-10 at 04:58 AM. Reason: typo.
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