linux-kernel - Re: [PATCH/RFC V8 1/1] clk: Support for clock parents and rates assigned from device tree

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Message-ID: <20140813203406.GU17528@sirena.org.uk>
Date:	Wed, 13 Aug 2014 21:34:06 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Mike Turquette <mturquette@...aro.org>
Cc:	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	devicetree@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-spi@...r.kernel.org, wsa@...-dreams.de,
	linux-arm-kernel@...ts.infradead.org, pawel.moll@....com,
	mark.rutland@....com, galak@...eaurora.org,
	gregkh@...uxfoundation.org, kyungmin.park@...sung.com,
	m.szyprowski@...sung.com, t.figa@...sung.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH/RFC V8 1/1] clk: Support for clock parents and rates
 assigned from device tree

On Fri, Jul 25, 2014 at 02:42:31PM -0700, Mike Turquette wrote:
> Quoting Sylwester Nawrocki (2014-07-03 10:25:53)

> > I would appreciate a DT, SPI or the I2C maintainer opinions.

> Yes, Acks from SPI and I2C maintainers would be good. I might need to
> drop those parts of this patch if they don't come through :-(

So, I just noticed this.  The reason I didn't see this earlier is that
it was buried at the end of a large clock API patch rather than a split
out patch for the SPI subsystem so it fell towards the bottom of
my review queue.  There seems to be no dependency on adding the feature
as part of one commit so it should really have been split out.

Please don't assume that people are going to look in detail at patches
that aren't obviously for them - I know I end up ignoring a lot of what
I get sent since I get CCed on a lot of random things for no apparent
reason (or get tediously large numbers of resends of things that are
tangentially related), I imagine others do the same.  If you're doing
that please draw attention to it, splitting out per subsystem is the
best way of doing that.

This is particularly unfortunate since I am actually a bit confused as
to why we need to open code this for every bus rather than doing it in
the driver core, there doesn't seem to be anything at all bus specific
going on here.  Why can't we just call this from the driver core?
Having the feature work for some buses and not others is going to get
old fast.

It's also not clear to me why we're passing false to of_clk_set_defaults()
when we do call it - it's quite common for I2C and SPI devices to be
clock providers and have clock trees.  As far as I can tell the
reasoning is that what's actually going on here is that this is actually
a mechanism to defer the initialisation to adding of the clock providers
in which case contrary to the documentation for the function it's
actually about device registration.  Is that right?

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