linux-kernel - Re: [PATCH 02/10] dt-bindings: net: can: grcan: Convert GRCAN CAN controllers binding from txt to YAML

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Message-ID: <13d562aa-3425-4753-a78f-dd268dd78794@gaisler.com>
Date: Thu, 11 Dec 2025 11:11:16 +0100
From: Arun Muthusamy <arun.muthusamy@...sler.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
 mkl@...gutronix.de, mailhol@...nel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-can@...r.kernel.org
Subject: Re: [PATCH 02/10] dt-bindings: net: can: grcan: Convert GRCAN CAN
 controllers binding from txt to YAML

Hi Krzysztof,

Thank you for your thorough review. I’d like to clarify a few points 
regarding the DT binding and get your guidance.

On 11/18/25 12:01, Krzysztof Kozlowski wrote:
> On 18/11/2025 10:21, Arun Muthusamy wrote:
>> +      Fallback on node name matching for systems that don't provide compatible.
>> +    enum:
>> +      - GAISLER_GRCAN
>> +      - 01_03d
>> +      - GAISLER_GRHCAN
>> +      - "01_034"
> This does not really work. Are you really defining here "name" property?

The driver supports two of the platforms which are LEON and NOEL 
platforms. PROM-based *LEON* systems identify uses the "node name" 
property, while DTS based *NOEL* systems use proper "|compatible"|strings. On LEON (SPARC32), AMBA Plug & Play information creates the DT 
properties, and drivers historically match devices based on node names.
To reflect this, I updated the $nodename pattern to support LEON-style 
node names: properties:
   $nodename:
     pattern: "^(GAISLER_GRCAN|01_03d|GAISLER_GRHCAN|01_034)$" I’d 
appreciate any suggestions on the preferred way to describe this node 
name for PROM-based LEON.

>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  freq:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    description: |
>> +      Frequency of the external oscillator clock in Hz (the frequency of the
>> +      amba bus in the ordinary case).
>> +      This property should be used by systems that utilize the common clock
>> +      framework is not supported.
> Missing systemid. Your commit msg must explain any changes done to the
> binding during conversion.

The driver now reads systemid directly from /ambapp0, so the property no 
longer needs to be defined in the DTS. The previous documentation was 
outdated and should have been updated after commit:
1e93ed26acf0 ("can: grcan: grcan_probe(): fix broken system id check for 
errata workaround needs").

>> +  - reg
>> +  - interrupts
> Where is freq? It was required in the old binding. Again, you need to
> explain the changes.

LEON: relies on the freq property
NOEL: uses a standard clocks binding
Because of this dual approach, the freq property is no longer required 
in the DTS binding itself as theAMBA Plug & Play creates the DT properties.

Thanks,

-- 
BR,

Arun Muthusamy
Software Engineer
Frontgrade Gaisler
T : +46 (0) 700 558 528
arun.muthusamy@...sler.com

Frontgrade Gaisler AB, Kungsgatan 12, SE-411 19 GÖTEBORG, Sweden.
+46 (0) 31 775 8650,www.gaisler.com <http://www.gaisler.com/>