linux-kernel - Re: [PATCH 4/7] spi: spi-fsl-dspi: avoid preparing the clock two times

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Message-ID: <20150127130117.GU21293@sirena.org.uk>
Date:	Tue, 27 Jan 2015 13:01:17 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
Cc:	mark.rutland@....com, stefan@...er.ch, shawn.guo@...aro.org,
	robh+dt@...nel.org, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux@....linux.org.uk, B44548@...escale.com,
	Li.Xiubo@...escale.com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-spi@...r.kernel.org
Subject: Re: [PATCH 4/7] spi: spi-fsl-dspi: avoid preparing the clock two
 times

On Tue, Jan 27, 2015 at 04:27:21PM +0530, Bhuvanchandra DV wrote:
> regmap_read/regmap_write will expect the peripheral clock
> to be enabled before accessing the registers of the peripheral.
> Since the peripheral clock is enabled separatly, avoid redundant clock
> prepare (with devm_regmap_init_mmio_clk) and use devm_regmap_init_mmio instead.

What's the advantage of this?  The clock API is refcounted so there
should be no issue with this and it seems like it's opening us up to
bugs if there's a path where we interact with the registers without
enabling the clocks.

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