[PATCH] arm64: dts: Add idle-states for Juno

[lorenzo.pieralisi@arm.com (Lorenzo Pieralisi)]

On Thu, Apr 30, 2015 at 05:40:35PM +0100, Jon Medhurst (Tixy) wrote:
> On Thu, 2015-04-30 at 17:00 +0100, Sudeep Holla wrote:
> > 
> > On 30/04/15 14:57, Jon Medhurst (Tixy) wrote:
> > > From: Jon Medhurst <tixy@linaro.org>
> > >
> > > Signed-off-by: Jon Medhurst <tixy@linaro.org>
> > > ---
> > >
> > > These have been kicking around out of tree for ages, any reason they
> > > shouldn't be in mainline?
> > 
> > One possible reason could be that these values are not tuned(e.g.
> > latency values, can they be same for both clusters ?)
> 
> I thought that both clusters being the same was questionable.
> 
> >  Though these
> > reasons are not blocking and this patch will not cause any
> > functionality break even if is merged as is.
> 
> My main purpose with trying to get this merged is so that people using
> Juno for general testing and validation will actually have cpuidle
> running and so potentially find more bugs.

I am reluctant to enable idle states in the default Juno dts, they
will affect latencies and performance tests significantly. I should
find a way to disable them by default and possibly have a DT property
to enabled them explicitly, we can't merge the dts as it is we have
to change the CPUidle code first.

Lorenzo

> 
> If we wait until ARM have finished tweaking their firmware and tuning
> benchmark runs to get 'optimum' values for their main usecases then I
> suspect we'll be waiting a long time ;-)
> 
> -- 
> Tixy
>