[Intel-gfx] screen is set to maximum brightness on initramfs module load

Ali Gholami Rudi aliqrudi at gmail.com
Sun Feb 7 20:06:20 CET 2010


Pedro Ribeiro <pedrib at gmail.com> wrote:
> Actually that's wrong. It also flashes when I boot into X. However, it
> quickly (somehow) gets restored to the default brightness. Maybe its
> gnome-settings-daemon or something...

I had another look at 965 intel docs vol 3.  I cannot find anything
to fetch the default backlight.  I traced the value of BLC_PWM_CTL2
and BLC_PWM_CTL.  The former is always 0xe0000000.  When booting
BLC_PWM_CTL reads as 0x8b678b67 (the duty cycle part equals the
frequency part) then it changes to 0x8b670000 (zero duty cycle) and
finally back to 0x8b678b66.  I'm wondering how the xorg driver
reads the default brightness.


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