linux-kernel - Re: [PATCH 2/2] dt-bindings: pinctrl: mcp23s08: Add multi-chip example

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260114-woodoo-ubiquitous-turtle-bddbee@quoll>
Date: Wed, 14 Jan 2026 10:21:40 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Jean-Michel Hautbois <jeanmichel.hautbois@...eli.org>
Cc: Linus Walleij <linusw@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Himanshu Bhavani <himanshu.bhavani@...iconsignals.io>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: pinctrl: mcp23s08: Add multi-chip
 example

On Tue, Jan 13, 2026 at 03:29:48PM +0100, Jean-Michel Hautbois wrote:
> Enable gpio-line-names property in the schema and add example showing
> how to use it with multiple MCP23S08/17/18 chips sharing the same SPI
> chip select. Names are assigned sequentially in hardware address order.
> 
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@...eli.org>
> ---
>  .../bindings/pinctrl/microchip,mcp23s08.yaml       | 33 ++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pinctrl/microchip,mcp23s08.yaml b/Documentation/devicetree/bindings/pinctrl/microchip,mcp23s08.yaml
> index e07f4723de17..667be31b6da3 100644
> --- a/Documentation/devicetree/bindings/pinctrl/microchip,mcp23s08.yaml
> +++ b/Documentation/devicetree/bindings/pinctrl/microchip,mcp23s08.yaml
> @@ -42,6 +42,8 @@ properties:
>    interrupts:
>      maxItems: 1
>  
> +  gpio-line-names: true

Variable number of GPIOs? No constraints possible at all? 

> +
>    reset-gpios:
>      description: GPIO specifier for active-low reset pin.
>      maxItems: 1
> @@ -159,3 +161,34 @@ examples:
>              microchip,spi-present-mask = /bits/ 8 <0x01>;
>          };
>      };
> +
> +  - |
> +    /* Multiple chips sharing same SPI CS with gpio-line-names */
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        gpio@0 {
> +            compatible = "microchip,mcp23s17";
> +            reg = <0>;
> +            gpio-controller;
> +            #gpio-cells = <2>;
> +            spi-max-frequency = <10000000>;
> +            /* Two chips at hardware addresses 0 and 1 */
> +            microchip,spi-present-mask = /bits/ 8 <0x03>;
> +            /*
> +             * Names assigned sequentially in address order.
> +             * First 16 names for chip at address 0 (GPA0-7, GPB0-7).
> +             * Next 16 names for chip at address 1 (GPA0-7, GPB0-7).
> +             */
> +            gpio-line-names =

Just extend existing example. There is little point in adding one new
example per one new different property.

Best regards,
Krzysztof