[PATCH] soc: renesas: rcar-rst: keep RESBAR2S in default state

[PATCH] soc: renesas: rcar-rst: keep RESBAR2S in default state

[Wolfram Sang]

Unlike Gen2, Gen4 has bit 15 of WDTRSTCR register also used. Keep it in
the default state for the V3U firmware workaround.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/soc/renesas/rcar-rst.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/renesas/rcar-rst.c b/drivers/soc/renesas/rcar-rst.c
index 7ba02f3a4a4f..0541990901fc 100644
--- a/drivers/soc/renesas/rcar-rst.c
+++ b/drivers/soc/renesas/rcar-rst.c
@@ -12,6 +12,7 @@
 
 #define WDTRSTCR_RESET		0xA55A0002
 #define WDTRSTCR		0x0054
+#define GEN4_WDTRSTCR_RESET	0xA55A8002
 #define GEN4_WDTRSTCR		0x0010
 
 #define CR7BAR			0x0070
@@ -30,7 +31,7 @@ static int rcar_rst_enable_wdt_reset(void __iomem *base)
 
 static int rcar_rst_v3u_enable_wdt_reset(void __iomem *base)
 {
-	iowrite32(WDTRSTCR_RESET, base + GEN4_WDTRSTCR);
+	iowrite32(GEN4_WDTRSTCR_RESET, base + GEN4_WDTRSTCR);
 	return 0;
 }
 
-- 
2.47.2

Re: [PATCH] soc: renesas: rcar-rst: keep RESBAR2S in default state

[Geert Uytterhoeven]

Hi Wolfram,

On Fri, 17 Oct 2025 at 13:42, Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Unlike Gen2, Gen4 has bit 15 of WDTRSTCR register also used. Keep it in
> the default state for the V3U firmware workaround.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

BTW, did you experience any ill effects from accidentally clearing
this bit? IIRC Falcon (and Spider) still rebooted fine before.
Perhaps you need it to make subsequent reboots work?

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] soc: renesas: rcar-rst: keep RESBAR2S in default state

[Wolfram Sang]

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Hi Geert,

> BTW, did you experience any ill effects from accidentally clearing
> this bit? IIRC Falcon (and Spider) still rebooted fine before.
> Perhaps you need it to make subsequent reboots work?

I didn't experience problems, found it in the datasheets while working
with S4 and watchdogs. I'd think a likely issue is that
MD-switch-changes might not be detected after a soft reboot?

Happy hacking,

   Wolfram


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Re: [PATCH] soc: renesas: rcar-rst: keep RESBAR2S in default state

[Geert Uytterhoeven]

Hi Wolfram,

On Mon, 20 Oct 2025 at 21:46, Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> > BTW, did you experience any ill effects from accidentally clearing
> > this bit? IIRC Falcon (and Spider) still rebooted fine before.
> > Perhaps you need it to make subsequent reboots work?
>
> I didn't experience problems, found it in the datasheets while working
> with S4 and watchdogs. I'd think a likely issue is that
> MD-switch-changes might not be detected after a soft reboot?

Thanks, I also see no ill effects on the remote Gray Hawk Single
that has old firmware and thus relies on commit accde57f464304cf
("[TEST] soc: renesas: rcar-rst: Enable WDT reset on early R-Car V4M")
in renesas-drivers.

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
i.e. will queue in renesas-devel for v6.19.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds