From: Imre Deak <imre.deak@intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 2/3] tests/pm_rps: vlv: load gpu for idle min/max tests
Date: Fri, 05 Dec 2014 23:01:52 +0200 [thread overview]
Message-ID: <1417813312.21713.3.camel@ideak-mobl> (raw)
In-Reply-To: <20141205205618.GA20350@phenom.ffwll.local>
On Fri, 2014-12-05 at 21:56 +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@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 ...
It isn't the current frequency that's changed but the min/max limits. If
by changing those the current frequency gets out of bound the kernel
properly changes the current frequency too.
> -Daniel
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next prev parent reply other threads:[~2014-12-05 21:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-04 16:09 [PATCH 0/3] igt/pm_rps: fix some subcases for vlv Imre Deak
2014-12-04 16:09 ` [PATCH 1/3] tests/pm_rps: vlv: wait for freq to settle Imre Deak
2014-12-04 16:09 ` [PATCH 2/3] tests/pm_rps: vlv: load gpu for idle min/max tests Imre Deak
2014-12-05 20:56 ` Daniel Vetter
2014-12-05 20:59 ` Chris Wilson
2014-12-05 21:06 ` Daniel Vetter
2014-12-05 21:01 ` Imre Deak [this message]
2014-12-04 16:09 ` [PATCH 3/3] tests/pm_rps: vlv: round middle point to freq supported by HW Imre Deak
2014-12-04 16:31 ` Ville Syrjälä
2014-12-05 14:27 ` [PATCH v2 " Imre Deak
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