Strange effect with i915 backlight controller
zonque at gmail.com
Fri Nov 4 07:36:16 PDT 2011
I'm facing a bug on a Samsung X20 notebook which features an i915
chipset (output of 'lspci -v' attached).
The effect is that setting the backlight to odd values causes the value
to be misinterpreted. Harald Hoyer (cc:) had the same thing on a Netbook
(I don't recall which model it was).
So this will turn the backlight to full brightness:
# cat /sys/class/backlight/intel_backlight/max_brightness
# echo 29750 > /sys/class/backlight/intel_backlight/brightness
However, writing 29749 will turn the display backlight off, and 29748
appears to be the next valid lower value.
It seems like the IS_PINEVIEW() branch in
could do the right thing, but this code is written for an entirely
different model, right?
I can reproduce this on 3.0 and 3.1 vanilla as well as with the current
Let me know if there is any patch that I can test.
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