[alsa-devel] [PATCH v5] ASoC: cs53l30: Add support for Cirrus Logic CS53L30

[Handrigan, Paul]

On 5/31/16, 12:10 PM, "Caleb Crome" <caleb at crome.org> wrote:

>On Tue, May 31, 2016 at 9:53 AM, Mark Brown <broonie at kernel.org> wrote:
>>
>> On Tue, May 17, 2016 at 04:43:33PM -0700, Nicolin Chen wrote:
>>
>> > In this case, would it be more appropriate to create one single DAI
>> > with channels_max = 4 over here?
>>
>> Yes.
>>
>> > Another question is for its TDM support. This chip outputs 4-channel
>> > data on two data output pins (SDOUT1 and SDOUT2) as normal mode; it
>> > outputs 4-channel data on one data output pin (SDOUT1) as TDM mode.
>> > However, the mode selection for a 4-channel recording should depend
>> > on the hardware design: whether the SDOUT2 is connected or not. So
>> > I am wondering if there is a common way or existing way to indicate
>> > this hardware design. Or just by simply defining a new DT property?
>>
>> That's a really rare thing to have as an option, most things either do
>> TDM or parallel data signals but not both.
>
>
>Interesting comment.  While I'm sure that's true for the moment,
>microphone arrays are changing this quickly.  I fall into the oddball
>category that the main chips I use are the TLV320AIC34 and CS53L30,
>and both of them can switch between TDM mode or dual I2S mode for 4
>channel support.
>
>Since I need to get many channels on board, and SoCs (except for TI)
>rarely have enough parallel I2S ports for mic arrays, I opt for TDM
>mode often.
>
>If you're using the CS53L30, chances are high that you're building a
>mic array.  Then the question is, how many microphones?  up to 4, you
>could live with dual I2S if your chip supports it.  Beyond 4, you're
>almost certainly talking TDM, unless you have a TI McASP with lots of
>inputs, or an XMOS part with multiple I2S interfaces.
>
>Of course, it's highly dependent on what the SoC supports.  I would
>say it's just about mandatory for the CS53L30 driver in particular to
>be able to switch between TDM or I2S mode based on a DT setting
>because of the huge variability of capabilities on the SoC side.   A
>TI McBSP could support multiple I2S busses, but a freescale SSI must
>use TDM mode.
>
>-Caleb

For this device you are using either I2S or TDM, therefore, it will
depend on the capabilities of the SoC (hence the hardware design).
This will not require a DT property since it is configured by the
cs53l30_set_dai_fmt callback.  As Calib mentioned, you will have to
use TDM if you are using greater than channels up to 16 channels for
a mic array.
 
>
>
>
>>
>>
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