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Message-ID: <CAMuHMdVL1U=yFdRA6diav8f9DTHPunesvPk1VxxWeaM+9KhjJA@mail.gmail.com>
Date: Tue, 19 Sep 2023 11:27:04 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
linux-renesas-soc@...r.kernel.org,
Andi Shyti <andi.shyti@...nel.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFT 1/2] i2c: rcar: reset controller is mandatory for Gen3+
Hi Wolfram,
On Tue, Sep 19, 2023 at 11:19 AM Wolfram Sang
<wsa+renesas@...g-engineering.com> wrote:
> > > + ret = reset_control_status(priv->rstc);
> > > + if (ret < 0)
> > > + return ret;
> >
> > This is a pre-existing check, but do you really need it?
> > This condition will be true if the reset is still asserted, which
> > could happen due to some glitch, or force-booting into a new kernel
> > using kexec. And AFAIUI, that should be resolved by the call to
> > rcar_i2c_do_reset() above.
>
> This check is needed to ensure reset_control_status() really works
> because we need it in rcar_i2c_do_reset(). From the docs:
>
> "reset_control_status - returns a negative errno if not supported,..."
>
> The code only checks for that, not for the status of the reset line.
Right, I missed the negative.
I don't think this can fail on R-Car Gen2+ (using the CPG/MSSR driver)
if devm_reset_control_get_exclusive() succeeded, but it's prudent, in
case the block is every reused on a different SoC family.
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
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