i915 backlight failure on resume with 2.6.27

James Bottomley James.Bottomley at HansenPartnership.com
Mon Dec 1 09:42:05 PST 2008

You probably remember the system, it's my fujitsu P7120 lifebook with
the funny backlight wiring.

Previously, suspend/resume was made to work by saving the PCI state
including the legacy backlight register setting (and worked just fine
when invoked with a hal quirk).

On FC9, with the 2.6.26 fedora kernels, hal no longer does anything and
relies on the i915 kernel driver.  This was perfectly fine, except that
the backlight was now being restored to full brightness on resume rather
than the setting on resume.  The other annoyance was that VT consoles
were now lost on resume (switching to them produces a black screen,
although switching back to vt7 where X is running is fine).

As of the 2.6.27 fedora kernels, the backlight is now off on resume,
which is even more annoying.  It can be turned on by doing a VT switch,
although all the console VTs are still blank, so there looks to be some
bug in the i915 driver that crept in between 2.6.26 and 2.6.27.


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