linux-kernel - Re: [PATCH v3 0/6] Add support to retrieve the bootstatus from watchdog for RZ/V2H(P) SoC

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Message-ID: <20250114200335.GA1626474-robh@kernel.org>
Date: Tue, 14 Jan 2025 14:03:35 -0600
From: Rob Herring <robh@...nel.org>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Prabhakar <prabhakar.csengg@...il.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>,
	Magnus Damm <magnus.damm@...il.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v3 0/6] Add support to retrieve the bootstatus from
 watchdog for RZ/V2H(P) SoC

On Mon, Jan 13, 2025 at 11:38:08AM +0000, Biju Das wrote:
> Hi Prabhakar,
> 
> > -----Original Message-----
> > From: Prabhakar <prabhakar.csengg@...il.com>
> > Sent: 13 January 2025 11:24
> > Subject: [PATCH v3 0/6] Add support to retrieve the bootstatus from watchdog for RZ/V2H(P) SoC
> > 
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > 
> > Hi All,
> > 
> > This patch series adds SYSCON support to retrieve boot status information for RZ/V2H(P) SoC.
> > Summary of Changes,
> > 
> >     Clock:
> >         Add syscon compatible support to the CPG block in bindings and
> >         device trees.
> > 
> >     Watchdog:
> >         Document the renesas,r9a09g057-syscon-wdt-errorrst property.
> >         Update the watchdog driver to fetch and report boot status via
> >         Error Reset Registers (CPG_ERROR_RSTm).
> > 
> >     Device Tree:
> >         Add the syscon property to CPG and WDT nodes in R9A09G057 and
> >         R9A09G047 SoC DTSI.
> > 
> > These changes enable the watchdog driver to identify boot sources like Power-on Reset and Watchdog
> > Reset, improving system diagnostics.
> 
> This means that, we should assume U-boot/bootloader should not clear the WDT reset status bit.
> 
> If they clear it, there should be a way to propagate it from u-boot/bootloader to linux,
> otherwise, we get wrong bootstatus in linux.
> But the clearing of watchdog status by one of the cases: 
> 
> 1) u-boot identify the boot source and clear the status bit
> 2) u-boot identify the boot source and does not clear the status bit, but linux clear it.
> 3) u-boot does not touch WDT status bits, but linux clear it.

Sounds like the same problem as this[1]. If that works for you, please 
comment there. Always better if there is more than 1 user for something 
"common".

Rob

[1]https://lore.kernel.org/devicetree-spec/48defa98-9718-4997-86cb-b171187708a6@cherry.de/T/#u