Re: [PATCH v3] [RFC] arm: use PSCI if available

From: Rob Herring
Date: Thu Mar 28 2013 - 11:04:14 EST


On 03/28/2013 09:51 AM, Nicolas Pitre wrote:
> On Thu, 28 Mar 2013, Stefano Stabellini wrote:
>
>> - the interface to bring up secondary cpus is different and based on
>> PSCI, in fact Xen is going to add a PSCI node to the device tree so that
>> Dom0 can use it.
>>
>> Oh wait, Dom0 is not going to use the PSCI interface even if the node is
>> present on device tree because it's going to prefer the platform smp_ops
>> instead.
>
> Waitaminute... I must have missed this part.
>
> Who said platform specific methods must be used in preference to PSCI?

I did. Specifically, I said the platform should be allowed to provide
its own smp_ops. A platform may need to do addtional things on top of
PSCI for example.

> If DT does provide PSCI description, then PSCI should be used. Doing
> otherwise is senseless. If PSCI is not to be used, then it should not
> be present in DT.

You can't assume the DT and kernel are in-sync. For example, I've added
PSCI in the firmware and DTB (part of the firmware), but the highbank
kernel may or may not use it depending if I convert it.

Rob

>
>
> Nicolas
>
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