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Date: Tue, 30 Jan 2024 17:02:50 +0000
From: Conor Dooley <conor@kernel.org>
To: William Qiu <william.qiu@starfivetech.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>,
	"linux-can@vger.kernel.org" <linux-can@vger.kernel.org>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Rob Herring <robh+dt@kernel.org>,
	Wolfgang Grandegger <wg@grandegger.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Marc Kleine-Budde <mkl@pengutronix.de>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>
Subject: Re: [PATCH v1 2/4] dt-bindings: can: Add bindings for CAST CAN
 Controller
Message-ID: <20240130-extruding-yodel-8580cc390b64@spud>
References: <20240129031239.17037-1-william.qiu@starfivetech.com>
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On Tue, Jan 30, 2024 at 06:30:54AM +0000, William Qiu wrote:
> > From: Conor Dooley <conor@kernel.org>
> > On Mon, Jan 29, 2024 at 11:12:37AM +0800, William Qiu wrote:

> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - cast,can
> > > +      - cast,canfd
> >=20
> > I don't like these uber generic compatibles that have no users as a fal=
lback.
> > Allowing them in the binding only really discourages people from creati=
ng device
> > specific compatibles.
> > Secondly, this is some purchased IP that I am sure has a versioning sch=
eme and
> > the compatibles that you have created do not reflect that.
> > If they were being used as a fallback, I would request some versioning.
> > That's not going to really work though since the canfd features on the
> > jh7110 require setting u0_can_ctrl_can_fd_enable, so neither of these
> > compatibles really has a use right now.
> >=20
> I'll add some tag to do versioning.

I don't want to see a "cast,can-<something>" compatible allowed in
isolation either as there is no user for it.
The generic compatibles like that should only be permitted in
combination with a device specific one - particularly since there are
bits in implementation defined registers that control whether or not
canfd is enabled.

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