linux-kernel - Re: [Xen-devel] [RFC/WIP] xen: clk: introudce pvclk for device passthrough

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Message-ID: <20160119011806.GA12932@linux-7smt.suse>
Date:	Tue, 19 Jan 2016 09:18:08 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	George Dunlap <George.Dunlap@...citrix.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	xen-devel <xen-devel@...ts.xenproject.org>,
	Ian Campbell <ian.campbell@...rix.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Julien Grall <julien.grall@...rix.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	linux-clk@...r.kernel.org
Subject: Re: [Xen-devel] [RFC/WIP] xen: clk: introudce pvclk for device
 passthrough

Hello George,

On Mon, Jan 18, 2016 at 11:22:44AM +0000, George Dunlap wrote:
>On Sat, Jan 16, 2016 at 5:22 AM, Peng Fan <van.freenix@...il.com> wrote:
>> This patch was just a initial patch, not sure whether this way
>> is ok from you side for handlding clk when doing platform device
>> passhthrough. Any comments are appreciated, and your comments may
>> give me a better direction.
>
>Hey Peng,
>
>Just speaking from the perspective of a Xen dev who's not an ARM dev:
>a few more words on the relationship between pvclk and
>device-passthrough would be helpful to set the context.  It sounds
>like:
>
>* On ARM, passing through a device requires a clocksource (at least
>for many devices)
>
>* dom0 has the hardware clocksource, but at the moment domUs don't
>have a suitable clocksource
>
>* This patch implements pvclk front/backend suitable for such devices
>
>Is that right?  In which case something like the following would be helpful:

Yeah. right. You have a better explaination than me :)

>
>"This patch introduces pvclk, a paravirtualized clock source suitable
>for devices to use when passing through to domUs on ARM systems."
>
>(Obviously change it as necessary to make it accurate.)

I'll add your words into the commit log.

Thanks,
Peng.

>
>Thanks,
> -George