linux-kernel - Re: [PATCH v3 1/2] dt-bindings: reset: syscon-reboot: support reset modes

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Message-ID: <20250227132644.GA1924628-robh@kernel.org>
Date: Thu, 27 Feb 2025 07:26:44 -0600
From: Rob Herring <robh@...nel.org>
To: André Draszik <andre.draszik@...aro.org>
Cc: Sebastian Reichel <sre@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Peter Griffin <peter.griffin@...aro.org>,
	Tudor Ambarus <tudor.ambarus@...aro.org>,
	Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com,
	linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: reset: syscon-reboot: support reset
 modes

On Thu, Feb 27, 2025 at 10:46:13AM +0000, André Draszik wrote:
> Add support for specifying different register/mask/value combinations
> for different types of reset.
> 
> In particular, update the binding to allow platforms to specify the
> following reset modes: soft, warm, cold, hard.
> 
> Linux can perform different types of reset using its reboot= kernel
> command line argument, and some platforms also wish to reset
> differently based on whether or not e.g. contents of RAM should be
> retained across the reboot.
> 
> The new properties match the existing properties, just prefixed with
> one of the reset modes mentioned above.

This would be why we don't do "simple" or "generic" bindings. There's 
always one more variation needing yet more properties to handle it. We 
also draw the line at encoding register accesses into DT. If we wanted 
that, we would have created a language for doing that (or started using 
Forth in FDT).

You need a specific binding for your h/w. If you can make it work with a 
"generic" driver, then that's great, but that's an OS decision which can 
change if needed. The binding can't change.

Rob