Re: [PATCH v2 1/4] dt-bindings: rtc: ingenic: Rework compatible strings and add #clock-cells

[Paul Cercueil]

Hi Rob,

Le lun. 31 oct. 2022 à 14:23:41 -0500, Rob Herring <robh@xxxxxxxxxx> a 
écrit :
> On Fri, Oct 28, 2022 at 11:55:16PM +0100, Paul Cercueil wrote:
> >  The RTC in the JZ4770 is compatible with the JZ4760, but has an 
> > extra
> >  register that permits to configure the behaviour of the CLK32K pin. 
> > The
> >  same goes for the RTC in the JZ4780.
> >
> >  Therefore, the ingenic,jz4770-rtc and ingenic,jz4780-rtc strings do 
> > not
> >  fall back anymore to ingenic,jz4760-rtc. The ingenic,jz4780-rtc 
> > string
> >  now falls back to the ingenic,jz4770-rtc string.
>
> This is a compatibility mess. There is no driver support in v6.1-rc 
> for
> ingenic,jz4770-rtc, so a new DT would not work with existing kernels. 
> It
> sounds like you need 3 compatibles for 4780.

Do newer DTs need to work with older kernels? I always assumed the 
compatibility was only enforced for the other way around.

If that's the case though, I guess I can enforce 3 compatibles for 4780 
and 2 for 4770 like  you suggested.

Cheers,
-Paul

> >  Additionally, since the RTCs in the JZ4770 and JZ4780 support 
> > outputting
> >  the input oscillator's clock to the CLK32K pin, the RTC node is now 
> > also
> >  a clock provider on these SoCs, so a #clock-cells property is added.
> >
> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >
> >   v2: - add constraint on which SoCs can have the #clock-cells 
> > property
> >       - add JZ4780 example which has a #clock-cells
> >
> >   .../devicetree/bindings/rtc/ingenic,rtc.yaml  | 32 
> > +++++++++++++++++--
> >   1 file changed, 30 insertions(+), 2 deletions(-)