linux-kernel - Re: [PATCH 1/2] clk: renesas: rzg2l: Deassert reset on assert timeout

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Message-ID: <CAMuHMdWdDQLYHm825t5Z3r2cwhUHAkMdgbhuF4oKhUqvnddHgw@mail.gmail.com>
Date: Wed, 7 Jan 2026 12:16:21 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Biju <biju.das.au@...il.com>
Cc: Michael Turquette <mturquette@...libre.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Stephen Boyd <sboyd@...nel.org>, Biju Das <biju.das.jz@...renesas.com>, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH 1/2] clk: renesas: rzg2l: Deassert reset on assert timeout

Hi Biju,

On Mon, 8 Dec 2025 at 11:14, Biju <biju.das.au@...il.com> wrote:
> From: Biju Das <biju.das.jz@...renesas.com>
>
> If the assert() fails due to timeout error, set the reset register bit
> back to deasserted state. This change is needed especially for handling
> assert error in suspend() callback that expect the device to be in
> operational state in case of failure.
>
> Signed-off-by: Biju Das <biju.das.jz@...renesas.com>

Thanks for your patch!

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

However, I am wondering what you think about the alternative below?

> --- a/drivers/clk/renesas/rzg2l-cpg.c
> +++ b/drivers/clk/renesas/rzg2l-cpg.c
> @@ -1669,8 +1669,11 @@ static int __rzg2l_cpg_assert(struct reset_controller_dev *rcdev,
>
>         ret = readl_poll_timeout_atomic(priv->base + reg, value,
>                                         assert == !!(value & mask), 10, 200);

If this loop would use its own "u32 mon" instead of reusing "value"...

> -       if (ret && !assert) {
> +       if (ret) {

... then "value" would still have the wanted state here...

>                 value = mask << 16;
> +               if (assert)
> +                       value |= mask;
> +

... and you can just switch back to the old state using:

    value ^= mask;

>                 writel(value, priv->base + CLK_RST_R(info->resets[id].off));
>         }
>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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