Re: [PATCH] dt-bindings: power: reset: restart-handler: add common schema

From: Sebastian Reichel
Date: Mon Sep 12 2022 - 06:29:11 EST


Hi,

On Wed, Sep 07, 2022 at 06:32:18PM +0200, Pali Rohár wrote:
> On Wednesday 07 September 2022 14:36:30 Krzysztof Kozlowski wrote:
> > Add common schema for restart and shutdown handlers, so they all use
> > same meaning of "priority" field. The Linux drivers already have this
> > property and some systems want to customize it per-board in DTS.
> >
> > Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> >
> > ---
> >
> > See also:
> > https://lore.kernel.org/all/8fe93da3-f768-16ae-7025-1cfa97a42b27@xxxxxxxxxx/
> > https://lore.kernel.org/all/20220831081715.14673-1-pali@xxxxxxxxxx/
> > ---
> > .../bindings/power/reset/gpio-restart.yaml | 13 ++------
> > .../bindings/power/reset/restart-handler.yaml | 30 +++++++++++++++++++
> > 2 files changed, 33 insertions(+), 10 deletions(-)
> > create mode 100644 Documentation/devicetree/bindings/power/reset/restart-handler.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml b/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
> > index a72d5c721516..d3d18e0f5db3 100644
> > --- a/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
> > +++ b/Documentation/devicetree/bindings/power/reset/gpio-restart.yaml
> > @@ -25,6 +25,9 @@ description: >
> > inactive-delay, the GPIO is driven active again. After a delay specified by wait-delay, the
> > restart handler completes allowing other restart handlers to be attempted.
> >
> > +allOf:
> > + - $ref: restart-handler.yaml#
> > +
> > properties:
> > compatible:
> > const: gpio-restart
> > @@ -41,16 +44,6 @@ properties:
> > in its inactive state.
> >
> > priority:
> > - $ref: /schemas/types.yaml#/definitions/uint32
> > - description: |
> > - A priority ranging from 0 to 255 (default 129) according to the following guidelines:
> > -
> > - 0: Restart handler of last resort, with limited restart capabilities.
> > - 128: Default restart handler; use if no other restart handler is expected to be available,
> > - and/or if restart functionality is sufficient to restart the entire system.
> > - 255: Highest priority restart handler, will preempt all other restart handlers.
> > - minimum: 0
> > - maximum: 255
> > default: 129
> >
> > active-delay:
> > diff --git a/Documentation/devicetree/bindings/power/reset/restart-handler.yaml b/Documentation/devicetree/bindings/power/reset/restart-handler.yaml
> > new file mode 100644
> > index 000000000000..f5d22ca0cd45
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/power/reset/restart-handler.yaml
> > @@ -0,0 +1,30 @@
> > +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/power/reset/restart-handler.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Restart and shutdown handler generic binding
> > +
> > +maintainers:
> > + - Sebastian Reichel <sre@xxxxxxxxxx>
> > +
> > +description:
> > + Restart and shutdown handler device is responsible for powering off the
> > + system, e.g. my cutting off the power. System might have several restart
> > + handlers, which usually are tried from most precise to last resort.
> > +
> > +properties:
> > + priority:
> > + $ref: /schemas/types.yaml#/definitions/uint32
>
> IIRC priority is signed integer number, not unsigned.
>
> > + description: |
> > + A priority ranging from 0 to 255 according to the following guidelines::
> > + 0: Restart handler of last resort, with limited restart capabilities.
> > + 128: Typical, default restart handler; use if no other restart handler
> > + is expected to be available, and/or if restart functionality is
> > + sufficient to restart the entire system.
> > + 255: Highest priority restart handler, will preempt all other restart handlers.
> > + minimum: 0
> > + maximum: 255
>
> And IIRC also other values (above 255 or below 0) are allowed for tuning
> two "highest" or two "last resort" handlers.
>
> This needs to be checked / tested to ensure that new schema is not incorrect.

priority is blindly copied into the priority field of struct
notifier_block, which is of type int. But that is an implementation
detail. I think the proposal from Krzysztof looks good. But let's
wait a bit to give Rob a chance to review.

-- Sebastian

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