[Intel-gfx] [PATCH 2/3] tests/pm_rps: vlv: load gpu for idle min/max tests

[Chris Wilson]

On Fri, Dec 05, 2014 at 09:56:18PM +0100, Daniel Vetter wrote:
> On Thu, Dec 04, 2014 at 06:09:39PM +0200, Imre Deak wrote:
> > When changing the sysfs GT min/max frequencies, the kernel won't
> > explicitly change the current frequency, unless it becomes out of bound
> > based on the new min/max values. The test happens to work on non-VLV
> > platforms because on those the kernel resets the current frequency
> > unconditionally (to adjust the RPS interrupt mask as a side-effect) and
> > that will lead to an RPS interrupt setting the minimum frequency.
> > 
> > To fix this load the GPU after decreasing the min frequency and before
> > checking the current frequency. This should set the current frequency to
> > the minimum.
> > 
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> 
> Isn't this a kernel bug which should be fixed in the kernel? If userspace
> changes the requested freq, the kernel should obey right away. Not
> somewhen later when something happens ...

Only if busy. If the GPU is idle, we should ignore the softlimits and
program the most efficient idle frequency - as part of i915.powersave.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre