linux-kernel - Re: [PATCH v10 02/10] dt-bindings: power: reset: Document reboot-mode cookie

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Message-ID: <20250710224740.GA15385-robh@kernel.org>
Date: Thu, 10 Jul 2025 17:47:40 -0500
From: Rob Herring <robh@...nel.org>
To: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
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Subject: Re: [PATCH v10 02/10] dt-bindings: power: reset: Document
 reboot-mode cookie

On Thu, Jul 10, 2025 at 02:45:44PM +0530, Shivendra Pratap wrote:
> Update the reboot-mode binding to support an optional cookie
> value in mode-<cmd> properties. The cookie is used to supply
> additional data for reboot modes that accept two arguments.
> 
> Signed-off-by: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
> ---
>  .../devicetree/bindings/power/reset/reboot-mode.yaml         | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml b/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
> index 3ddac06cec7277789b066d8426ea77d293298fac..a4d2fe1db51e0c1f34ebefddaad82b8cc0b1b34a 100644
> --- a/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
> +++ b/Documentation/devicetree/bindings/power/reset/reboot-mode.yaml
> @@ -10,14 +10,15 @@ maintainers:
>    - Andy Yan <andy.yan@...k-chips.com>
>  
>  description: |
> -  This driver get reboot mode arguments and call the write
> -  interface to store the magic value in special register
> -  or ram. Then the bootloader can read it and take different
> -  action according to the argument stored.
> +  This driver gets reboot mode arguments and calls the write
> +  interface to store the magic and an optional cookie value
> +  in special register or ram. Then the bootloader can read it
> +  and take different action according to the argument stored.
>  
>    All mode properties are vendor specific, it is a indication to tell
>    the bootloader what to do when the system reboots, and should be named
> -  as mode-xxx = <magic> (xxx is mode name, magic should be a non-zero value).
> +  as mode-xxx = <magic cookie> (xxx is mode name, magic should be a
> +  non-zero value, cookie is optional).

I don't understand the distinction between magic and cookie... Isn't all 
just magic values and some platform needs more than 32-bits of it?

>  
>    For example, modes common Android platform are:
>      - normal: Normal reboot mode, system reboot with command "reboot".
> @@ -45,5 +46,6 @@ examples:
>        mode-recovery = <1>;
>        mode-bootloader = <2>;
>        mode-loader = <3>;
> +      mode-edl = <1 2>;
>      };
>  ...
> 
> -- 
> 2.34.1
>