Re: [PATCH v2 1/4] dt-bindings: power: reset: add PSCRR NVMEM recorder binding

[Faruque Ansari]

Hi Krzysztof,

On 27-Aug-26 3:15 PM, Krzysztof Kozlowski wrote:
> On Wed, Aug 19, 2026 at 10:50:43PM +0530, Faruque Ansari wrote:
> > Add binding for the PSCRR NVMEM recorder. Records the power state
> > change reason into a small NVMEM cell, such as a PMIC SDAM byte or
> > RTC scratch register — so the cause survives a power cycle and can be
> > read back on the next boot.
>
> A nit, subject: drop second/last, redundant "binding". The
> "dt-bindings" prefix is already stating that these are bindings.
> See also:
> https://elixir.bootlin.com/linux/v7.1-rc7/source/Documentation/devicetree/bindings/submitting-patches.rst#L23
Thanks for the review.
I'll fix this in V3.

> > Signed-off-by: Faruque Ansari <faruque.ansari@xxxxxxxxxxxxxxxx>
> > ---
> >   .../bindings/power/reset/pscrr-nvmem.yaml          | 59 ++++++++++++++++++++++
> >   MAINTAINERS                                        |  1 +
> >   2 files changed, 60 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml
> > new file mode 100644
> > index 000000000000..5334c923d644
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/power/reset/pscrr-nvmem.yaml
> > @@ -0,0 +1,59 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/power/reset/pscrr-nvmem.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: NVMEM Power State Change Reason recorder
> > +
> > +maintainers:
> > +  - Faruque Ansari <faruque.ansari@xxxxxxxxxxxxxxxx>
> > +  - Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
> > +
> > +description:
> > +  An NVMEM-backed recorder for Power State Change Reasons (PSCRR). Persists
> > +  the reboot or shutdown cause into a small NVMEM cell, such as an RTC
> > +  scratch register, a PMIC SDAM (Scratch Data Access Memory) byte, or an
> > +  EEPROM — so the reason survives a power cycle and can be read back on the
> > +  next boot. The cell is referenced via the standard nvmem-cells consumer
> > +  binding.
>
> I do not see how this should be a separate device. This should be rather part
> of PSCRR, reboot handler or just the nvmem. Otherwise it is just device
> node for instantiating driver.

There's already precedent in-tree for exactly this shape of 
binding: 
Documentation/devicetree/bindings/power/reset/nvmem-reboot-mode.yaml 
defines a standalone "nvmem-reboot-mode" compatible whose sole 
purpose is to bind an nvmem-cell and instantiate a driver that 
writes a reboot-mode value into it before reset, for the 
bootloader to read.

pscrr-nvmem follows the same pattern: instead of a reboot-mode 
value for the bootloader, it records the PSCRR reason into an 
NVMEM cell before reset and reads it back on the next boot for 
PSCRR to report. Like nvmem-reboot-mode, it works with any NVMEM 
backend (RTC scratch register, PMIC SDAM, EEPROM, etc.).

It doesn't fit cleanly into PSCRR core (hardware-agnostic, no 
NVMEM dependency today) or a specific reset handler (it only 
records the reason, it doesn't initiate the reset).


Thanks,
Faruque Ansari