Re: [PATCH v2 2/7] dt-bindings: can: mpfs: add missing required clock

[Conor Dooley]

On Mon, Jan 22, 2024 at 03:46:04PM +0100, Marc Kleine-Budde wrote:
> On 22.01.2024 14:21:04, Conor Dooley wrote:
> > On Mon, Jan 22, 2024 at 02:13:16PM +0100, Marc Kleine-Budde wrote:
> > > On 22.01.2024 12:19:50, Conor Dooley wrote:
> > > > From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> > > > 
> > > > The CAN controller on PolarFire SoC has an AHB peripheral clock _and_ a
> > > > CAN bus clock. The bus clock was omitted when the binding was written,
> > > > but is required for operation. Make up for lost time and add it.
> > > > 
> > > > Cautionary tale in adding bindings without having implemented a real
> > > > user for them perhaps.
> > > > 
> > > > Fixes: c878d518d7b6 ("dt-bindings: can: mpfs: document the mpfs CAN controller")
> > > > Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> > > > ---
> > > >  .../devicetree/bindings/net/can/microchip,mpfs-can.yaml     | 6 ++++--
> > > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/net/can/microchip,mpfs-can.yaml b/Documentation/devicetree/bindings/net/can/microchip,mpfs-can.yaml
> > > > index 45aa3de7cf01..01e4d4a54df6 100644
> > > > --- a/Documentation/devicetree/bindings/net/can/microchip,mpfs-can.yaml
> > > > +++ b/Documentation/devicetree/bindings/net/can/microchip,mpfs-can.yaml
> > > > @@ -24,7 +24,9 @@ properties:
> > > >      maxItems: 1
> > > >  
> > > >    clocks:
> > > > -    maxItems: 1
> > > > +    items:
> > > > +      - description: AHB peripheral clock
> > > > +      - description: CAN bus clock
> > > 
> > > What about adding clock-names, so that the order can be checked
> > > automatically?
> > 
> > I don't personally care for doing so, but if your heart is set on having
> > them, then sure.
> 
> Usually the CAN driver needs to have the clock rate of the clocks that
> the basis for the CAN bus clock. Looking at the clocks description it's
> probably the 2nd one.
> 
> With clock-names we can automatically check that the 2nd clock is always
> the CAN clock.

I think we already had this discussion on v1, where I said that the
binding requires the clocks to be in that order, regardless of whether
or not clock-names is provided. You feel more strongly about it than I
do, so I will add them when I get around to sending a v3.

Cheers,
Conor.

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