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

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Message-ID: <ZMgWqVb4wg5h6poh@smile.fi.intel.com>
Date:   Mon, 31 Jul 2023 23:16:41 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Nikita Shubin <nikita.shubin@...uefel.me>
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

On Fri, Jul 28, 2023 at 01:01:11PM +0300, Nikita Shubin wrote:
> On Fri, 2023-07-28 at 12:46 +0300, Andy Shevchenko wrote:

...

> I see your point now - citing docs:
> 
> "Logic safeguards are included to condition the control signals for
> power connection to the matrix to prevent part damage. In addition, a
> software lock register is included that must be written with 0xAA
> before each register write to change the values of the four switch
> matrix control registers."
> 
> So reading SHOULDN'T affect the lock.
> 
> But as we checked reading also breaks the lock, that's why this looks
> so odd, it was done for purpose - i'll check it once again anyway.

This is very interesting information! Please, document this somewhere in
the code.

-- 
With Best Regards,
Andy Shevchenko