linux-kernel - Re: [PATCH 2/6] dt-bindings: can: mcp25xxfd: document device tree bindings

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Date:   Tue, 29 Sep 2020 12:06:24 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Wolfgang Grandegger <wg@...ndegger.com>,
        Rob Herring <robh+dt@...nel.org>, linux-can@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dev.kurt@...dijck-laurijssen.be,
        Thomas Kopp <Thomas.Kopp@...rochip.com>
Subject: Re: [PATCH 2/6] dt-bindings: can: mcp25xxfd: document device tree
 bindings

On 9/29/20 11:46 AM, Geert Uytterhoeven wrote:
> Hi Manivannan, Oleksij,
> 
> On Thu, Sep 10, 2020 at 11:37 PM Manivannan Sadhasivam
> <manivannan.sadhasivam@...aro.org> wrote:
>> From: Oleksij Rempel <o.rempel@...gutronix.de>
>>
>> This patch adds the device-tree binding documentation for the Microchip
>> MCP25xxFD SPI CAN controller family.
>>
>> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
>> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
>> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> Thanks for your patch, which is now commit 1b5a78e69c1fdae9
> ("dt-binding: can: mcp25xxfd: document device tree bindings") in net-next.
> 
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/can/microchip,mcp25xxfd.yaml
>> @@ -0,0 +1,79 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/net/can/microchip,mcp25xxfd.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title:
>> +  Microchip MCP2517FD and MCP2518FD stand-alone CAN controller device tree
>> +  bindings
>> +
>> +maintainers:
>> +  - Marc Kleine-Budde <mkl@...gutronix.de>
>> +
>> +properties:
>> +  compatible:
>> +    oneOf:
>> +      - const: microchip,mcp2517fd
>> +        description: for MCP2517FD
>> +      - const: microchip,mcp2518fd
>> +        description: for MCP2518FD
>> +      - const: microchip,mcp25xxfd
>> +        description: to autodetect chip variant
> 
> The last one is a wildcard?
> When would you want to use it (oh, in the example below)?

Im using it in overlays for several raspi hats, e.g. a raspi to click board
converter where I add mcp2517fd or mcp2518fd modules without the need to change
the overlay.

> Can you guarantee Microchip will not introduce other components that
> match this wildcard, but are not compatible?

Guarantee is quite a strong word :)

So far in that name space there are the mcp2510, mcp2515 and mcp25625. From the
SW point of view the 2515 and 25625 are identical while being compatible to the
mcp2510 but offer more features. There's a single drver (mcp251x) for these.
These chips implement the CAN-2.0 standard.

Regarding the mcp2517fd and mcp2518fd, the "fd" in the name references the
CAN-FD standard (successor to CAN-2.0).

Maybe Thomas Kopp (Cc'ed) from Microchip can say something to this.

We can rename the compatible to mcp251xfd to make it more specific.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



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