linux-kernel - Re: [RFC PATCH 0/3] Add new reg_update

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Message-ID: <CAK8P3a1rWuL-mSeFBN0Dk7u3wnDmPgknEM3Em734KP64-Wv0ZQ@mail.gmail.com>
Date:   Thu, 9 Apr 2020 11:15:41 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Baolin Wang <baolin.wang7@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>, Mark Brown <broonie@...nel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Lyra Zhang <zhang.lyra@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/3] Add new reg_update_bits() support

On Thu, Apr 9, 2020 at 10:58 AM Baolin Wang <baolin.wang7@...il.com> wrote:
>
> The Spreadtrum platform uses a special set/clear method to update
> registers' bits, thus this patch set introduces a new reg_update_bits()
> callback, as well as adding a helper in syscon driver to support
> this feature.
>
> Any comments are welcome. Thanks.

This looks like a good idea to me, both the concept and the implementation.

The one thing I'd note is that we have a similar mechanism for devices made
by Sigmatel and later Freescale after they acquired them.
include/linux/stmp_device.h only holds a couple of definitions, so it's much
less abstract than your approach, but the idea is similar.

It would be nice in theory to move the sigmatel devices over to
reg_update_bits() in theory, but this seems unlikely to actually happen,
given that these are mostly obsolete drivers at this point.

      Arnd