linux-kernel - Re: [PATCH v3 07/42] soc: Add SoC driver for Cirrus ep93xx

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Message-ID: <79619e92b70fdb4b324758ddb34f84b3b8963256.camel@maquefel.me>
Date:   Fri, 28 Jul 2023 12:28:05 +0300
From:   Nikita Shubin <nikita.shubin@...uefel.me>
To:     Andy Shevchenko <andy@...nel.org>
Cc:     Alexander Sverdlin <alexander.sverdlin@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 07/42] soc: Add SoC driver for Cirrus ep93xx

Hello Andy!

On Fri, 2023-07-21 at 17:13 +0300, Andy Shevchenko wrote:
> On Thu, Jul 20, 2023 at 02:29:07PM +0300, Nikita Shubin via B4 Relay
> wrote:
> > From: Nikita Shubin <nikita.shubin@...uefel.me>
> > +       spin_lock_irqsave(&ep93xx_swlock, flags);
> > +
> > +       regmap_read(map, EP93XX_SYSCON_DEVCFG, &val);
> > +       val &= ~clear_bits;
> > +       val |= set_bits;
> > +       regmap_write(map, EP93XX_SYSCON_SWLOCK,
> > EP93XX_SWLOCK_MAGICK);
> > +       regmap_write(map, EP93XX_SYSCON_DEVCFG, val);
> 
> Is this sequence a must?
> I.o.w. can you first supply magic and then update devcfg?
> 

Unfortunately it is a must to write EP93XX_SYSCON_SWLOCK and only then
the next write to swlocked registers will succeed.