RE: Re: [PATCH v3] ASoC: dt-bindings: imx-card: Add dsp_a DAI format

[Chancel Liu]

> > Existing i.MX audio sound card described by this binding use codecs
> > that operate in i2s or dsp_b formats. The newly added CS42448 codec
> > requires dsp_a for its TDM interface. To properly describe such
> > hardware in DT, the binding needs to allow dsp_a DAI format.
> >
> > Only i2s, dsp_b and dsp_a are included because these are the formats
> > actually used by the hardware supported by this binding. Other formats
> > such as left_j, right_j, ac97 are not used or required by the hardware
> 
> "pdm", "left_j", "right_j" are supported by SAI, so I think they should be
> added from the hardware point of view.
> 
> Best regards
> Shengjiu Wang

You're right. The binding should describe the full hardware capability
rather than only the formats currently used on a specific board or by
the current driver.

SAI is the controller of i.MX audio sound card. Therefore, the binding
must enumerate all formats that the SAI hardware is capable of, 
regardless of current usage. According to the SAI specification, the
following DAI formats are supported:
- i2s
- right_j
- left_j
- dsp_a
- dsp_b
- pdm
- msb
- lsb

I will update the binding in v4 to include all of these formats.

Regards, 
Chancel Liu

> > currently covered by this binding, so they are intentionally not added.
> >
> > Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx>
> > ---
> > Changes in v3:
> > - Rewrote commit message completely to describe hardware requirements.
> > Explicitly documented why only dsp_a is added and why other formats
> > are not included.
> > - Rebased on latest code base. No functional changes.
> >
> > Changes in v2:
> > - Updated commit message to explain current support for i2s and dsp_b
> > formats and new support for dsp_a. No code changes.
> >
> >  Documentation/devicetree/bindings/sound/imx-audio-card.yaml | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/sound/imx-audio-card.yaml
> > b/Documentation/devicetree/bindings/sound/imx-audio-card.yaml
> > index 5424d4f16f52..75757fbccd89 100644
> > --- a/Documentation/devicetree/bindings/sound/imx-audio-card.yaml
> > +++ b/Documentation/devicetree/bindings/sound/imx-audio-card.yaml
> > @@ -37,6 +37,7 @@ patternProperties:
> >          items:
> >            enum:
> >              - i2s
> > +            - dsp_a
> >              - dsp_b
> >
> >        dai-tdm-slot-num: true
> > --
> > 2.50.1
> >