Re: [PATCH v7 3/8] drivers: cpuidle: implement DT based idle states infrastructure

Lorenzo Pieralisi
2014-08-14T16:02:12Z

On Thu, Aug 14, 2014 at 04:47:57PM +0100, Nicolas Pitre wrote:
> On Thu, 14 Aug 2014, Lorenzo Pieralisi wrote:
>
> > On Wed, Aug 13, 2014 at 06:29:49PM +0100, Nicolas Pitre wrote:
> > > So if you tell me a messed-up DT won't bear much consequences then I'm
> > > fine with that.
> >
> > Nico, on second thoughts, since Ashwin raised the point too and I think
> > that at these early stages it might turn out useful, I gave coding
> > the check a go. I tried to make the check self contained so that we can
> > yank it out if we do not want it in the final version or we will want
> > to remove it later.
> >
> > Here the refreshed patch is:
> >
> > -- >8 --
> > Subject: [PATCH] drivers: cpuidle: implement DT based idle states
> > infrastructure
> >
> > On most common ARM systems, the low-power states a CPU can be put into are
> > not discoverable in HW and require device tree bindings to describe
> > power down suspend operations and idle states parameters.
> >
> > In order to enable DT based idle states and configure idle drivers, this
> > patch implements the bulk infrastructure required to parse the device tree
> > idle states bindings and initialize the corresponding CPUidle driver states
> > data.
> >
> > The parsing API accepts a start index that defines the first idle state
> > that should be initialized by the parsing code in order to give new and
> > legacy driver flexibility over which states should be parsed using the
> > new DT mechanism.
> >
> > The idle states list is obtained from the first cpu in the driver
> > cpumask, which implicitly means the parsing code expects idle states
> > (and related list of phandles) to be the same for all CPUs in the
> > CPUidle driver mask. The kernel does not check this assumption, it must
> > be enforced by the bootloader to ensure correct system behaviour.
>
> Is this last sentence still true?

Nope, you are right. Fixed the commit log, a stale comment in the code
and dt nodes ref counting, if I get no additional comments I will post
this patch with v8, that should be final.

Thank you !!!
Lorenzo