linux-kernel - Re: [PATCH] ARM: cpuidle: Support asymmetric idle definition

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Message-ID: <160c3091-2d10-9c7b-c55b-e76abf23653f@arm.com>
Date:   Wed, 31 May 2017 18:33:52 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>, rjw@...ysocki.net,
        lorenzo.pieralisi@....com, leo.yan@...aro.org,
        "open list:CPUIDLE DRIVERS" <linux-pm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: cpuidle: Support asymmetric idle definition



On 31/05/17 17:40, Daniel Lezcano wrote:

> Hi Sudeep, Lorenzo,
> 
> I have been thinking and looking at the domain-idle-state and I don't
> see an obvious connection between what is describing the power domain,
> the cpu idle driver and what we are trying to achieve.
>

I am not sure what you mean by *connection* above.

1. With old flat list of idle states, we should get the cpumask sharing
   the idle states from the phandle or something similar.
2. With new domain-idle-state and hierarchical DT binding, you just need
   to infer that from the hierarchy.

> I would like to suggest something much more simple, register a cpuidle
> driver per cpu, so every cpu can have its own idle definitions, that
> should work for dynamiQ, smp and hmp. The impact on the driver will be
> minimal.
> 

Sounds simple, but not sure if it's scalable on platforms with
relatively large number of CPUs like 48 or 96(e.g. Cavium Thunder
-- 
Regards,
Sudeep