linux-kernel - Re[10]: [PATCH v3] mfd: syscon: Add non-DT support

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Date:	Wed, 20 Feb 2013 16:47:52 +0400
From:	Alexander Shiyan <shc_work@...l.ru>
To:	Dong Aisheng <dong.aisheng@...aro.org>
Cc:	Arnd Bergmann <arnd@...db.de>,
	linux-kernel@...r.kernel.org,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re[10]: [PATCH v3] mfd: syscon: Add non-DT support

> On 20 February 2013 19:14, Arnd Bergmann <arnd@...db.de> wrote:
> > On Wednesday 20 February 2013, Dong Aisheng wrote:
> >> On 20 February 2013 18:06, Arnd Bergmann <arnd@...db.de> wrote:
> >> > I would first like to get an answer to the question I asked in my first mail,
> >> > which is what the use case of non-DT support in this driver is. If this
> >> > is used only by a new platform that has to use DT anyway, or by an existing
> >> > platform that is easy enough to convert, we probably shouldn't do all this
> >> > at all.
> >> >
> >>
> >> If the platform can convert to dt, then we do not have such issue.
> >> The question is do we allow the existing non-dt platforms to use it
> >> before converting?
> >
> > I think the answer to that is "it depends". It's basically a question of
> > how much work it would be to convert the platforms that need it over to
> > DT, and how much of the interface it actually needs. E.g. if there is
> > only one in-tree platform that needs to use syscon but can't easily be
> > moved over to DT, but that platform can only have a single syscon device,
> > then we don't need any of the matching support but could simply return
> > the first regmap area we have in the list.
> >
> > Of course, if the platform in question is out of tree, I would argue
> > that the whatever patches are needed by that platform should also
> > remain out of tree.
> >
> 
> Basically i agree with your point.
> Alexander seems to be the first non-dt user of syscon driver.
> He may answer whether they could choose to convert to dt first.
> But one question i wonder is that it may be hard to know how many poteintial
> non-dt platforms may use syscon.

OK. I can convert platform to DT, no so easy, but possible.
But I will use syscon as way to using DT (and MULTIPLATFORM in the future),
this mean that I should completely drop ATAG support from this platform
(since I cannot use syscon device without DT support, but several platform devices
need to use system-wide registers).
Arnd, if its OK for you, I will use this way. (I talking about CLPS711X, you know it :) ).

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