On Thu, 14 Aug 2014, Lorenzo Pieralisi wrote:

On Wed, Aug 13, 2014 at 06:29:49PM +0100, Nicolas Pitre wrote:

quoted

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?


Nicolas