linux-kernel - Re: [PATCH v4 2/9] bindings: ipmi: Add binding for IPMB device intf

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Message-ID: <Z4aUyX8g-JprzLpd@mail.minyard.net>
Date: Tue, 14 Jan 2025 10:46:01 -0600
From: Corey Minyard <corey@...yard.net>
To: Ninad Palsule <ninad@...ux.ibm.com>
Cc: minyard@....org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, andrew+netdev@...n.ch, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	openipmi-developer@...ts.sourceforge.net, netdev@...r.kernel.org,
	joel@....id.au, andrew@...econstruct.com.au,
	devicetree@...r.kernel.org, eajames@...ux.ibm.com,
	linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/9] bindings: ipmi: Add binding for IPMB device intf

On Mon, Jan 13, 2025 at 01:48:12PM -0600, Ninad Palsule wrote:
> Add device tree binding document for the IPMB device interface.
> This device is already in use in both driver and .dts files.
> 
> Signed-off-by: Ninad Palsule <ninad@...ux.ibm.com>
> ---
>  .../devicetree/bindings/ipmi/ipmb-dev.yaml    | 55 +++++++++++++++++++
>  1 file changed, 55 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml
> 
> diff --git a/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml b/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml
> new file mode 100644
> index 000000000000..136806cba632
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/ipmi/ipmb-dev.yaml
> @@ -0,0 +1,55 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/ipmi/ipmb-dev.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: The Intelligent Platform Management Bus(IPMB) Device
> +
> +description: |
> +  The IPMB is an I2C bus which provides interconnection between Baseboard

"Baseboard -> "a Baseboard"

> +  Management Controller(BMC) and chassis electronics. The BMC sends IPMI
> +  requests to intelligent controllers like Satellite Management Controller(MC)
> +  device via IPMB and the device sends a response back to the BMC.

device -> devices
"a response" -> responses

> +  This device binds backend Satelite MC which is a I2C slave device with the BMC

You use IPMB devices on both the BMC and the MCs.  The sentence above is
a little confusing, too.  How about:

This device uses an I2C slave device to send and receive IPMB messages,
either on a BMC or other MC.

> +  for management purpose. A miscalleneous device provices a user space program

Misspelling: miscellaneous

> +  to communicate with kernel and backend device. Some IPMB devices only support

"kernel" -> "the kernel"

> +  I2C protocol instead of SMB protocol.

the I2C protocol and not the SMB protocol.

Yes, the English language uses way too many articles...

That is a lot of detail, but it looks good beyond what I've commented
on.

> +
> +  IPMB communications protocol Specification V1.0
> +  https://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/ipmp-spec-v1.0.pdf
> +
> +maintainers:
> +  - Ninad Palsule <ninad@...ux.ibm.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - ipmb-dev
> +
> +  reg:
> +    maxItems: 1
> +
> +  i2c-protocol:
> +    description:
> +      Use I2C block transfer instead of SMBUS block transfer.
> +    type: boolean
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        ipmb-dev@10 {
> +            compatible = "ipmb-dev";
> +            reg = <0x10>;

I'm not sure of the conventions around device tree here, but the reg is
not used in the driver and it will always be the I2C address that
already in that node just one level up.  It does not serve any purpose
that I can see.  My suggestion would be to remove it.

-corey

> +            i2c-protocol;
> +        };
> +    };
> -- 
> 2.43.0
>