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

From: sugar <sugar.zhang@rock-chips.com>
To: Mark Brown <broonie@kernel.org>
Cc: alsa-devel@alsa-project.org, heiko@sntech.de,
	linux-kernel@vger.kernel.org, tiwai@suse.com,
	lgirdwood@gmail.com, linux-rockchip@lists.infradead.org,
	perex@perex.cz, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] ASoC: rockchip: i2s: add 8 channels capture and lrck-mode support
Date: Wed, 7 Oct 2015 16:01:38 +0800	[thread overview]
Message-ID: <5614D162.3020500@rock-chips.com> (raw)
In-Reply-To: <20150930184655.GX15635@sirena.org.uk>

Sorry for late reply, we were in the National Day Holiday.

在 10/1/2015 02:46, Mark Brown 写道:
> 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.
>

Got it, How about the following modify?

if (dai->symmetric_rates)
	regmap_update_bits(i2s->regmap, I2S_CKR,
                            I2S_CKR_TRCM_MASK,
                            I2S_CKR_TRCM(val));