linux-kernel - Re: [RFC PATCH] watchdog: rzv2h_wdt: Add support to retrieve the bootstatus information

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Message-ID: <CA+V-a8srdDkdAss2okuyfGYBwU5b9cF0aNw+KOSGR1wPquqNdQ@mail.gmail.com>
Date: Sat, 14 Dec 2024 21:36:11 +0000
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Guenter Roeck <linux@...ck-us.net>, Wim Van Sebroeck <wim@...ux-watchdog.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Rob Herring <robh@...nel.org>, 
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [RFC PATCH] watchdog: rzv2h_wdt: Add support to retrieve the
 bootstatus information

Hi Biju,

On Sat, Dec 14, 2024 at 11:32 AM Biju Das <biju.das.jz@...renesas.com> wrote:
>
> Hi Lad, Prabhakar,
>
<snip>
> > > That is a change in behavior. Up to now the syscon phandle did not
> > > have to exist for the driver to work. Is it guaranteed to not result
> > > in regressions on systems where it doesn't ? Also, is this documented ? I don't seem to be able to
> > find it.
> > >
> > Agreed. I will add a fallback mechanism to handle cases where the syscon property is not present in
> > the WDT node. This will ensure no regressions occur, and the bootstatus will simply be set to 0 in
> > such scenarios. As mentioned in the patch comments, I have not yet submitted the DT binding changes
> > because I wanted feedback on the syscon approach. The new RZ SoCs have registers scattered across
> > various locations, and I was exploring if there might be a better way to handle this.
>
> See, syscon compatible not needed with [1]
>
> [1]
> https://lore.kernel.org/all/20241211-syscon-fixes-v1-3-b5ac8c219e96@kernel.org/
>
As per my understanding, `syscon` compatible is required in this case
because the CPG driver does not register a regmap. With the patch [1]
(linked above), this applies to drivers that register a syscon regmap,
where the corresponding DT node does not necessarily need a `syscon`
compatible.

Cheers,
Prabhakar