linux-kernel - Re: [PATCH v8 1/4] dt-bindings: can: m

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Message-Id: <DC680MA7LMN0.33Q95D1CT5TVK@baylibre.com>
Date: Tue, 19 Aug 2025 09:20:28 +0200
From: "Markus Schneider-Pargmann" <msp@...libre.com>
To: "Marc Kleine-Budde" <mkl@...gutronix.de>
Cc: "Chandrasekar Ramakrishnan" <rcsekar@...sung.com>, "Rob Herring"
 <robh@...nel.org>, "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor
 Dooley" <conor+dt@...nel.org>, "Vishal Mahaveer" <vishalm@...com>, "Kevin
 Hilman" <khilman@...libre.com>, "Dhruva Gole" <d-gole@...com>, "Sebin
 Francis" <sebin.francis@...com>, "Kendall Willis" <k-willis@...com>,
 "Akashdeep Kaur" <a-kaur@...com>, "Simon Horman" <horms@...nel.org>,
 "Vincent MAILHOL" <mailhol.vincent@...adoo.fr>,
 <linux-can@...r.kernel.org>, <devicetree@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 1/4] dt-bindings: can: m_can: Add wakeup properties

Hi,

On Wed Aug 13, 2025 at 9:23 AM CEST, Marc Kleine-Budde wrote:
> On 12.08.2025 11:10:22, Markus Schneider-Pargmann wrote:
>> The pins associated with m_can have to have a special configuration to
>> be able to wakeup the SoC from some system states. This configuration is
>> described in the wakeup pinctrl state while the default state describes
>> the default configuration.
>> 
>> Also m_can can be a wakeup-source if capable of wakeup.
>> 
>> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
>> ---
>>  .../devicetree/bindings/net/can/bosch,m_can.yaml   | 22 ++++++++++++++++++++++
>>  1 file changed, 22 insertions(+)
>> 
>> diff --git a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
>> index c4887522e8fe97c3947357b4dbd4ecf20ee8100a..ecba8783198fc1658fcc236d8aa3c89d8c90abbd 100644
>> --- a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
>> +++ b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
>> @@ -106,6 +106,22 @@ properties:
>>          maximum: 32
>>      minItems: 1
>>  
>> +  pinctrl-0:
>> +    description: Default pinctrl state
>> +
>> +  pinctrl-1:
>> +    description: Wakeup pinctrl state
>> +
>> +  pinctrl-names:
>> +    description:
>> +      When present should contain at least "default" describing the default pin
>> +      states. The second state called "wakeup" describes the pins in their
>> +      wakeup configuration required to exit sleep states.
>> +    minItems: 1
>> +    items:
>> +      - const: default
>> +      - const: wakeup
>> +
>
> This breaks at least the stm32mp15 SoCs that define a sleep state:
>
> &m_can1 {
> 	resets = <&rcc FDCAN_R>;
> 	pinctrl-names = "default", "sleep";
> 	pinctrl-0 = <&m_can1_pins_b>;
> 	pinctrl-1 = <&m_can1_sleep_pins_b>;
> 	status = "okay";
> };

I am struggling to find binding documentation that explicitly lists
this sleep pinctrl state. So what is the intended purpose here? Also the
driver does nothing with this at the moment right?

I mean I can also add a sleep state to the binding or just leave the
binding empty so it can be anything, but that feels wrong.

Best
Markus

>
>>    power-domains:
>>      description:
>>        Power domain provider node and an args specifier containing
>> @@ -122,6 +138,12 @@ properties:
>>      minItems: 1
>>      maxItems: 2
>>  
>> +  wakeup-source:
>> +    $ref: /schemas/types.yaml#/definitions/phandle-array
>> +    description:
>> +      List of phandles to system idle states in which mcan can wakeup the system.
>> +
>> +
>
> One newline should be enough.
>
>>  required:
>>    - compatible
>>    - reg
>> 
>> -- 
>> 2.50.1
>> 
>> 
>> 
>
> Marc


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