From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rob Herring <robherring2@gmail.com>
Subject: Re: [PATCH v3] [RFC] arm: use PSCI if available
Date: Thu, 28 Mar 2013 10:04:04 -0500
Message-ID: <51545BE4.9050206@gmail.com>
References: <1364388639-11210-1-git-send-email-stefano.stabellini@eu.citrix.com> <20130327133811.GE18429@mudshark.cambridge.arm.com> <alpine.DEB.2.02.1303271610430.4430@kaball.uk.xensource.com> <20130327172306.GB20990@mudshark.cambridge.arm.com> <alpine.DEB.2.02.1303281225050.4430@kaball.uk.xensource.com> <alpine.LFD.2.03.1303281048060.1372@syhkavp.arg>
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To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, "linux@arm.linux.org.uk" <linux@arm.linux.org.uk>, "arnd@arndb.de" <arnd@arndb.de>, Marc Zyngier <Marc.Zyngier@arm.com>, Will Deacon <will.deacon@arm.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
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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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