Comment 6 for bug 1041315

This is very similar to earlier bug 47271, except an even later bios updated then broke it again. So this is the sequence of events:

 * Old bios : old kernel == works
 * bios upgrade (VBIOS 2132) : old kernel == broken
 * kernel upgrade (backport f47166d2) == fixed
 * bios upgrade == broken
 * kernel upgrade (3.2 or later) == works

We would like help identify which kernel commit fixes the problem again so that we can backport to 3.0. The interesting thing is if we _revert_ f47166d2 in the 3.0-stable branch with the latest bios, it works again. There is also a lot of info in the ubuntu bug.

This is only a bug in the 3.0 stable series, introduced by commit f47166d2 in bug 47271.

Diff in the regdump:

< GEN6_INSTDONE_1: 0xfffffffe
> GEN6_INSTDONE_1: 0x00000000
< PIPEACONF: 0xc0000054 (enabled, active, 6bpc)
> PIPEACONF: 0xc0000050 (enabled, active, 6bpc)
< DSPASURF: 0x0096b000
> DSPASURF: 0x04830008
< PCH_PP_CONTROL: 0x00000003 (blacklight disabled, power down on re=
set, panel on)
> PCH_PP_CONTROL: 0xabcd0003 (blacklight disabled, power down on re=
set, panel on)
< RC6_RESIDENCY_TIME: 0x0001b916
< RC6p_RESIDENCY_TIME: 0x00000000
> RC6_RESIDENCY_TIME: 0x00331e26
> RC6p_RESIDENCY_TIME: 0xf5d8388f