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

Hi Tommaso,

On Wed, 5 Aug 2026 at 13:56, Tommaso Merciai
<[email protected]> wrote:
> 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 <[email protected]>
> > >>> ---
> > >>>  .../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?

Isn't this output the single clock output of the sound module's clock
provider (#clocks-cells = <0>)? Hence can't the consumer driver set
the clock rate?

If the consumer driver cannot set the clock rate, but depends on a
fixed clock rate, it can configure this in DT using assigned-clocks
and assigned-clock-rates, right?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds