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

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Date: Mon, 22 Jan 2024 16:31:32 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Conor Dooley <conor@...nel.org>
Cc: linux-riscv@...ts.infradead.org, 
	Conor Dooley <conor.dooley@...rochip.com>, Daire McNamara <daire.mcnamara@...rochip.com>, 
	Wolfgang Grandegger <wg@...ndegger.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, linux-can@...r.kernel.org, 
	netdev@...r.kernel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 2/7] dt-bindings: can: mpfs: add missing required clock

On 22.01.2024 14:56:09, Conor Dooley wrote:
> 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@...rochip.com>
> > > > > 
> > > > > 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@...rochip.com>
> > > > > ---
> > > > >  .../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.

Yes, this discussion sounded very familiar to me, never mind. Keep it as
is, and let's get this binding and the CAN driver upstream!

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
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