Re: [PATCH 1/3] ASoC: dt-bindings: renesas,r9a09g047-sound: Document audio_clkout clock-frequency

[Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>]

On Tue, Aug 04, 2026 at 08:20:29AM +0200, Krzysztof Kozlowski wrote:
> On 03/08/2026 19:19, Tommaso Merciai wrote:
> > Hi Krzysztof,
> > Thanks for your review.
> > 
> > On Mon, Aug 03, 2026 at 03:32:48PM +0200, Krzysztof Kozlowski wrote:
> >> On 03/08/2026 15:28, Tommaso Merciai wrote:
> >>> r9a09g047e57-smarc.dts set clock-frequency for the audio_clkout output,
> >>> but the binding never declared it, so dtbs_check fails:
> >>>
> >>>   sound@13c00000 (renesas,r9a09g047-sound): Unevaluated properties
> >>>   are not allowed ('clock-frequency' was unexpected)
> >>
> >> Maybe the DTS is wrong, because property was rejected? Did you check
> >> this? You cannot document ABI post-factum if it was rejected.
> >>
> >>
> >>>
> >>> clock-cells is fixed to 0, so only a single audio_clkout applies.
> >>>
> >>> Fixes: a86fd3c20218 ("ASoC: dt-bindings: sound: Add DT binding for RZ/G3E sound")
> >>> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> >>> ---
> >>>  .../devicetree/bindings/sound/renesas,r9a09g047-sound.yaml     | 3 +++
> >>>  1 file changed, 3 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/sound/renesas,r9a09g047-sound.yaml b/Documentation/devicetree/bindings/sound/renesas,r9a09g047-sound.yaml
> >>> index d7fa16554698..6e2b2c93b4b7 100644
> >>> --- a/Documentation/devicetree/bindings/sound/renesas,r9a09g047-sound.yaml
> >>> +++ b/Documentation/devicetree/bindings/sound/renesas,r9a09g047-sound.yaml
> >>> @@ -42,6 +42,9 @@ properties:
> >>>    "#clock-cells":
> >>>      const: 0
> >>>  
> >>> +  clock-frequency:
> >>> +    description: for audio_clkout
> >>
> >> Incomplete, missing type/ref, constraints.
> > 
> > renesas,r9a09g047-sound is handled by sound/soc/renesas/rcar/core.c [1],
> > and "clock-frequency" is read by rsnd_adg_get_clkout() [2]. The same
> > property is already documented for R-Car in
> > Documentation/devicetree/bindings/sound/renesas,rsnd.yaml [3].
> 
> But was the property rejected? I am repeating myself...

Looking into this further, I found that you already asked to drop this
property during the v5 review [1].

Thanks for pointing it out.

For context: the sound module contains an audio clock generator (ADG) which
generates an output clock from the external audio clocks and outputs it in
to the AUDIO_CLKOUT pin, that mostly supply master clock to codec.

"clock-frequency" is array of the possible rates provided by
AUDIO_CLKOUT to the codec master clock.
Based on the playback rate it will request either 44.1kHz or 48kHz.

I will drop "clock-frequency" property from r9a09g047e57-smarc.dts, where
AUDIO_CLKOUT output pin is not wired.

But for boards that populates AUDIO_CLKOUT we need this property,
Could you suggest how to model this properly?

Thanks for your time.

[1] https://lore.kernel.org/all/20260417-energetic-practical-frigatebird-5b93ad@quoll/

Kind regards,
Tommaso

> 
> Best regards,
> Krzysztof