[Intel-gfx] [PATCH] drm/i915/cnl: WaForceContextSaveRestoreNonCoherent

[Oscar Mateo]

On 09/28/2017 02:46 AM, Chris Wilson wrote:
> Stealing the thread for another gem_workarounds conundrum.
>
> After a reset, we lose the RING_FORCE_TO_NONPRIV registers. If they
> where in the context image as we presumed, the values would be retained
> and they can be read back from before reset, so it's not the case of
> write-only register!
>
> So are they the mythical powercontext but require an LRI after reset to
> restore the settings for all logical contexts? Or can we make those into
> regular MMIO?
> -Chris

I cannot see these in any the context image formats, no matter the GEN, 
so I suspect they are regular (but privileged) MMIO registers. I think 
by "These are global registers and power context save/restored" they 
simply mean that they survive RC6.