linux-kernel - Re: [PATCH v2] misc: Driver for Silicon Labs Si570 and compatibles

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Message-Id: <201104261600.23675.arnd@arndb.de>
Date:	Tue, 26 Apr 2011 16:00:23 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	guenter.roeck@...csson.com
Cc:	"Hans J. Koch" <hjk@...sjkoch.de>,
	"Greg Kroah-Hartman" <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jonathan Cameron <kernel@...23.retrosnub.co.uk>,
	Randy Dunlap <rdunlap@...otime.net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] misc: Driver for Silicon Labs Si570 and compatibles

On Friday 22 April 2011, Guenter Roeck wrote:
> On Thu, 2011-04-21 at 19:34 -0400, Hans J. Koch wrote:
> > I don't think the UIO framework is the right place for such a thing. If it's
> > just this one driver that needs modification of a clock from userspace, then
> > a sysfs attribute could be added to that driver. If there are several drivers
> > that need this, then the clock framework should be extended.
> 
> Agreed. Also, the desire to control the clock frequency through such a
> driver (user mode or not) seems odd. Such an approach would be
> inherently non-scalable (for my part I would have to support two drivers
> already). Voltage regulators are not controlled through the drivers of
> the chips they are providing power to either, but have an independent
> existence.

I think you are talking about different things here. What I think
Hans was saying is that it should be in the specific UIO driver, not
in the framework, which I can agree with. If we get a bunch of these,
we can still make it generic at a later point, but that is not your
problem.

I think exporting the clock to kernel drivers as a struct clk is
the most useful approach to allow reuse, and then you just have to
interface to that from your existing UIO driver.

	Arnd
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