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

[Daniel Vetter]

On Fri, Dec 05, 2014 at 08:59:42PM +0000, Chris Wilson wrote:
> 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.

Hm yeah that slight reinterpretation of the limits makes them actually
more useful. So ack from me on all 3 patches.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch