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:
 <TY3PR01MB11346D7617436A7779B6697B3861F2@TY3PR01MB11346.jpnprd01.prod.outlook.com>
Date: Mon, 13 Jan 2025 11:38:08 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Prabhakar <prabhakar.csengg@...il.com>, Geert Uytterhoeven
	<geert+renesas@...der.be>, Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...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>
CC: "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

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.

Cheers,
Biju