linux-kernel - Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing output clock to codec

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Message-ID: <20141203192024.GL7712@sirena.org.uk>
Date:	Wed, 3 Dec 2014 19:20:24 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Jianqun Xu <jay.xu@...k-chips.com>
Cc:	lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.de,
	sonnyrao@...omium.org, heiko@...ech.de,
	linux-arm-kernel@...ts.infradead.org, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] ASoC: rockchip: i2s: add support for grabbing
 output clock to codec

On Wed, Dec 03, 2014 at 03:18:38PM +0800, Jianqun Xu wrote:
> From: Sonny Rao <sonnyrao@...omium.org>
> 
> We need to claim the clock which is driving the codec so that when we enable
> clock gating, we continue to clock the codec when needed.  I make this an
> optional clock since there might be some applications where we don't need it
> but can still use the I2S block.

I would expect that the clock for the CODEC should be managed by the
CODEC if at all possible - that seems more logical than having the CPU
I2S controller request and manage it if it's a separate clock.  Why add
this to the CPU side driver?

We've not always done this for older systems due to the lack of a usable
clock API but that's starting to be addressed.

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