drm/i915 3.5 merge window: gen6_sanitize_pm errors

[Daniel Vetter]

On Thu, May 24, 2012 at 07:27:04PM -0700, Linus Torvalds wrote:
> These guys seem to be recently introduced:
> 
>   [drm:gen6_sanitize_pm] *ERROR* Power management discrepancy:
> GEN6_RP_INTERRUPT_LIMITS expected 17000000, was 12060000
>   [drm:gen6_sanitize_pm] *ERROR* Power management discrepancy:
> GEN6_RP_INTERRUPT_LIMITS expected 17070000, was 17000000
> 
> This is on my SNB Macbook Air.
> 
> Everything seems to *work*, which makes me think:
> 
>  - that error isn't really so big a deal that you have to *SHOUT* about it.
> 
>  - I wonder how valid the discrepancy checking code is to begin with.
> 
> Hmm?

On snb/ivb we have a problem that the gpu turbo can get stuck, and most
often it gets stuck at the lowest frequency, resulting in unhappy users.
Chris noticed that this happens when the RP irq limit register reads a
bogus value (and eventually gets stuck). Although your machine looks
interesting, because usually we just read back 0.

I've already sent a pull request to Dave with our current best effort to
duct-tape over the problem. If that doesn't cut out the dmesg flood, I
guess we need to tune down that message a bit. But we've added it in that
obnoxious way in the first place to get bug reports, so that we actually
know how bad the problem is. Hence I'd like to keep it around a bit.

Cheers, Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48