Re: [PATCH 1/2] ASoC: rockchip: i2s: add 8 channels capture and lrck-mode support

From: Mark Brown <broonie@kernel.org>
To: sugar <sugar.zhang@rock-chips.com>
Cc: lgirdwood@gmail.com, perex@perex.cz, tiwai@suse.com,
	heiko@sntech.de, alsa-devel@alsa-project.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] ASoC: rockchip: i2s: add 8 channels capture and lrck-mode support
Date: Wed, 30 Sep 2015 19:46:55 +0100	[thread overview]
Message-ID: <20150930184655.GX15635@sirena.org.uk> (raw)
In-Reply-To: <5608F74C.3000104@rock-chips.com>

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On Mon, Sep 28, 2015 at 04:16:12PM +0800, sugar wrote:
> 在 9/24/2015 00:24, Mark Brown 写道:

> >My initial thought here is that the machine driver should be responsible
> >for setting this and then the DAI driver should check to see if
> >symmetric_rates are in use and configure itself appropriately.  Is there
> >a reason why this won't work here?

> It's for i2s ip configuration, in the most situation, there is no need
> to use this property, except one case:

> In order to save gpio pins for other function use, we may use single
> lrck(tx or rx) pin. of course, it depends on product design. when in i2s
> slave mode, we need to configure this to share lrck with tx/rx inside i2s
> logic.

> symmetric_rates flag works fine on rockchip platform, but it can't cover the
> above case.

> Do you have any suggestion about this or maybe there is no need to upstream
> this special part?

What makes you say that the symmetric_rates flag can't be used to cover
this case?  What you describe above is hte normal reason for needing to
enforce symmetric_rates.  The driver should be able to check if the flag
has been set just as well as the core is.

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