[PATCH] arm64: dts: renesas: ulcb-kf: document a problemw with old firmware

[PATCH] arm64: dts: renesas: ulcb-kf: document a problemw with old firmware

[Wolfram Sang]

Old firmware set the GPIO to output, so no interrupts could be read.
Newer firmware does this correctly. The exact version could not be
determined, sadly.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 arch/arm64/boot/dts/renesas/ulcb-kf.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi b/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi
index 84b0976503b7..45e55ce760d1 100644
--- a/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi
+++ b/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi
@@ -324,6 +324,7 @@ gpio_exp_77: gpio@77 {
 		reg = <0x77>;
 		gpio-controller;
 		#gpio-cells = <2>;
+		/* If these interrupts don't work, please update your firmware */
 		interrupt-controller;
 		interrupt-parent = <&gpio5>;
 		interrupts = <9 IRQ_TYPE_EDGE_FALLING>;
-- 
2.39.2

Re: [PATCH] arm64: dts: renesas: ulcb-kf: document a problemw with old firmware

[Geert Uytterhoeven]

Hi Wolfram,

On Tue, Jan 30, 2024 at 10:52 AM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Old firmware set the GPIO to output, so no interrupts could be read.
> Newer firmware does this correctly. The exact version could not be
> determined, sadly.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thanks for your patch!

> --- a/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi
> +++ b/arch/arm64/boot/dts/renesas/ulcb-kf.dtsi
> @@ -324,6 +324,7 @@ gpio_exp_77: gpio@77 {
>                 reg = <0x77>;
>                 gpio-controller;
>                 #gpio-cells = <2>;
> +               /* If these interrupts don't work, please update your firmware */
>                 interrupt-controller;
>                 interrupt-parent = <&gpio5>;
>                 interrupts = <9 IRQ_TYPE_EDGE_FALLING>;

I'd rather not add such comments (especially +6y after the fact), as
this is the standard operating procedure in case something doesn't work.

Do you think we should sprinkle the following, too??

/* If secondary CPUs don't work, please update your firmware */
/* If cpuidle crashes, please update your firmware */
/* If watchdog restart doesn't work, please update your firmware */
/* If PSCI reboot doesn't work, please update your firmware */

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] arm64: dts: renesas: ulcb-kf: document a problemw with old firmware

[Wolfram Sang]

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Hi Geert,

> I'd rather not add such comments (especially +6y after the fact), as
> this is the standard operating procedure in case something doesn't work.

Okay, can be argued.

> /* If secondary CPUs don't work, please update your firmware */
> /* If cpuidle crashes, please update your firmware */
> /* If watchdog restart doesn't work, please update your firmware */
> /* If PSCI reboot doesn't work, please update your firmware */

Actually, I wouldn't mind. It documents that we *know* updating firmware
helps in this particular case. But as said, I can see your point as
well. Let's drop this patch.

Happy hacking,

   Wolfram


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