linux-kernel - Re: [PATCH v3 14/42] power: reset: Add a driver for the ep93xx reset

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Date:   Sat, 11 Nov 2023 19:18:28 +0100
From:   Alexander Sverdlin <alexander.sverdlin@...il.com>
To:     Andy Shevchenko <andy@...nel.org>, nikita.shubin@...uefel.me
Cc:     Hartley Sweeten <hsweeten@...ionengravers.com>,
        Lennert Buytenhek <kernel@...tstofly.org>,
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Subject: Re: [PATCH v3 14/42] power: reset: Add a driver for the ep93xx reset

Hi Andy,

On Fri, 2023-07-21 at 19:37 +0300, Andy Shevchenko wrote:
> > +       /* Issue the reboot */
> > +       ep93xx_devcfg_set_clear(priv->map, EP93XX_SYSCON_DEVCFG_SWRST, 0x00);
> > +       ep93xx_devcfg_set_clear(priv->map, 0x00, EP93XX_SYSCON_DEVCFG_SWRST);
> 
> 
> > +       mdelay(1000);
> 
> Atomic?! Such a huge delay must be explained, esp. why it's atomic.

atomic or not, SoC is supposed to reset itself here.
However there is an errata [1] and the SoC can lockup instead.
So even pr_emerg() makes sense to me.

> > +       pr_emerg("Unable to restart system\n");
> > +       return NOTIFY_DONE;

[1] http://web.archive.org/web/20161130230727/http://www.cirrus.com/en/pubs/appNote/AN258REV2.pdf

-- 
Alexander Sverdlin.