linux-kernel - Re: [PATCH 2/4] clk: renesas: rzg2l: Re-assert reset on deassert timeout

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Message-ID: <aLb-dAiVgFk1LsXR@tom-desktop>
Date: Tue, 2 Sep 2025 16:25:56 +0200
From: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org,
	biju.das.jz@...renesas.com,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] clk: renesas: rzg2l: Re-assert reset on deassert
 timeout

Hi Geert,

On Tue, Sep 02, 2025 at 04:16:12PM +0200, Geert Uytterhoeven wrote:
> Hi Tommaso,
> 
> On Tue, 2 Sept 2025 at 15:51, Tommaso Merciai
> <tommaso.merciai.xr@...renesas.com> wrote:
> > On Tue, Sep 02, 2025 at 02:18:17PM +0200, Geert Uytterhoeven wrote:
> > > On Wed, 20 Aug 2025 at 12:05, Tommaso Merciai
> > > <tommaso.merciai.xr@...renesas.com> wrote:
> > > > Prevent issues during reset deassertion by re-asserting the reset if a
> > > > timeout occurs when trying to deassert. This ensures the reset line is in a
> > > > known state and improves reliability for hardware that may not immediately
> > > > clear the reset monitor bit.
> > > >
> > > > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
> > >
> > > > --- a/drivers/clk/renesas/rzg2l-cpg.c
> > > > +++ b/drivers/clk/renesas/rzg2l-cpg.c
> > > > @@ -1667,9 +1667,16 @@ static int __rzg2l_cpg_assert(struct reset_controller_dev *rcdev,
> > > >                 return 0;
> > > >         }
> > > >
> > > > -       return readl_poll_timeout_atomic(priv->base + reg, value,
> > > > -                                        assert ? (value & mask) : !(value & mask),
> > > > -                                        10, 200);
> > > > +       ret = readl_poll_timeout_atomic(priv->base + reg, value,
> > > > +                                       assert ? (value & mask) : !(value & mask),
> > > > +                                       10, 200);
> > > > +       if (ret && !assert) {
> > > > +               dev_warn(rcdev->dev, "deassert timeout, re-asserting reset id %ld\n", id);
> > > > +               value = mask << 16;
> > > > +               writel(value, priv->base + CLK_RST_R(info->resets[id].off));
> > > > +       }
> > >
> > > Is this an issue you've seen during actual use?
> > > Would it make sense to print warnings on assertion timeouts, too?
> >
> > I haven’t observed any assertion timeout issues during actual use,
> > so maybe printing warnings on assertion may not be necessary.
> > What do you think?
> 
> Have you seen deassertion timeouts?

I haven’t seen any deassertion timeouts either.

> I would rather not print a warning.  The error code would be propagated
> up anyway.

If for you is ok.
I will drop dev_warn() on both:

	- __rzg2l_cpg_assert()
	- __rzv2h_cpg_assert()

in v2.
Please gently le me know.

Thanks & Regards,
Tommaso

> 
> 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
>