Re: [PATCH 2/2] ASoC: dt-bindings: fsl-sai: Support Rx-only SAI

[Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>]

Hi Krzysztof,

Am Mittwoch, 20. Dezember 2023, 16:48:34 CET schrieb Krzysztof Kozlowski:
> On 19/12/2023 13:29, Alexander Stein wrote:
> > On SoC like i.MX8QXP some SAI IP cores support only Rx path. Allow
> > specifying only an Rx DMA channel, while omitting the Tx one.
> > 
> > Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > ---
> > The feature list in reference manual IMX8DQXPRM Rev. 0 05/2020
> > section 1.1.2 "Features" explicitly state that SAI2 and SAI3 is
> > receive only.
> 
> Why aren't you constraining it per variant/device? If only some have one
> DMA channel, then I would normally expect allOf:if:then narrowing it for
> each device.

I'm not sure I get what you want to constraint. In the very same SoC there are 
SAI IP instances supporting Rx & Tx while others support Rx only.
The feature list in RM IMX8DQXPRM Rev. 0 05/2020 states:
>  4x SAI (SAI0 and SAI1 are transmit/receive; SAI2 and SAI3 are receive only)

An actual example can be seen at [1].

Best regards,
Alexander

[1] https://lore.kernel.org/all/20231214150243.1991532-4-alexander.stein@xxxxxxxxxxxxxxx/

> Best regards,
> Krzysztof


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