Kernel Bug Tracker – Bug 15575
Netbook Philco PHN 10108 doesn't supported by kernel to change LCD brightness level
Last modified: 2013-12-10 18:16:07 UTC
When can't change the LCD brightness in my netboot. It works fine in native netbook's SO (Windows 7 Home Starter).
cygnus:~# cat /proc/acpi/video/IGD/LCD/brightness
cygnus:~# ls -l /sys/class/backlight/
cygnus:~# uname -a
Linux cygnus 2.6.34-rc1-git6 #1 SMP Thu Mar 18 13:46:34 BRT 2010 i686 GNU/Linux
cygnus:~# cat /etc/debian_version
cygnus:~# lsmod |grep video
uvcvideo 44183 0
videodev 26658 1 uvcvideo
v4l1_compat 10354 2 uvcvideo,videodev
i2c_core 12406 6 i915,drm_kms_helper,drm,i2c_algo_bit,videodev,i2c_i801
video 14805 1 i915
output 1196 1 video
usbcore 99096 5 uvcvideo,usb_storage,uhci_hcd,ehci_hcd
thermal_sys 9522 4 processor,video,thermal,fan
cygnus:~# hwinfo --monitor
26: None 00.0: 10002 LCD Monitor
[Created at monitor.95]
Unique ID: rdCR.98oPz6MbmnE
Hardware Class: monitor
Model: "CPT LCD Monitor"
Vendor: CPT "CPT"
Device: eisa 0x04c4
Size: 222x130 mm
Detailed Timings #0:
Horizontal: 1024 1072 1104 1200 (+48 +80 +176) -hsync
Vertical: 600 603 609 625 (+3 +9 +25) -vsync
Frequencies: 45.00 MHz, 37.50 kHz, 60.00 Hz
Config Status: cfg=new, avail=yes, need=no, active=unknown
Other informations are attached.
Thanks in advance.
Eriberto - Brazil
Created attachment 25596 [details]
Created attachment 25597 [details]
Created attachment 25598 [details]
Created attachment 25599 [details]
the backlight is not controlled via ACPI, i.e. no _BCM/_BCL/_BQC methods available.
can you change the backlight via xrandr?
please attach the full dmesg output of xrandr --verbose
Created attachment 25603 [details]
I can't control via xrandr. File attached.
This is not a Linux/ACPI bug because the backlight is not controlled via ACPI.
IMO, the problem is that the graphics driver fully rely on the backlight sysfs I/F, and doesn't support the native backlight switching any more.
Matthew wrote a patch to fix this, but I don't know the current status.
Zhang, Must I wait a reply from Intel team?
let's wait for Matthew's comments first. :p
Ok Zhang. Thanks a lot for your help. I will wait. Bye!
Opsss... In my original message: 's/When can't change the LCD brightness/I can't change the LCD brightness/'
Created attachment 25804 [details]
Native backlight support for Intel
This adds native backlight support for Intel. It's against drm-intel, so will probably only apply to 2.6.34-rc kernels. The backlight type support really needs to go upstream before this is mergable.
Dupe of https://bugs.freedesktop.org/show_bug.cgi?id=26664, closing.
| Should be fixed by building the upstream samsung-laptop drivers.
Unfortunately, Eriberto's machine is from Philco, not Samsung.
Missing backlight driver is something for the acpi guys to beat their head against.
From comment #8, 2010:
| This is not a Linux/ACPI bug because the backlight is not controlled via ACPI.
| IMO, the problem is that the graphics driver fully rely on the backlight sysfs
| I/F, and doesn't support the native backlight switching any more.
| Matthew wrote a patch to fix this, but I don't know the current status.
Assigning to platform-driver-x86.