linux-kernel - Re: [PATCH v3 0/6] RTL8231 GPIO expander support

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Message-ID: <e10c8ef7f758b4f7fa0fcbc992c84125@walle.cc>
Date:   Tue, 01 Jun 2021 12:18:39 +0200
From:   Michael Walle <michael@...le.cc>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Sander Vanheule <sander@...nheule.net>,
        Andrew Lunn <andrew@...n.ch>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/6] RTL8231 GPIO expander support

Am 2021-06-01 11:59, schrieb Linus Walleij:
> Just regarding all registers/memory cells in a register page
> as default volatile (which is what we do a lot of the time)
> has its upsides: bugs like this doesn't happen.

I don't think this is the bug here. If it is really a write-only 
register
the problem is the read in RMW. Because reading the register will return
the input value instead of the (previously written) output value.

-michael