linux-kernel - Re: [PATCH] regmap: prevent noinc writes from clobbering cache

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Date:   Wed, 1 Nov 2023 20:24:45 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Ben Wolsieffer <ben.wolsieffer@...ring.com>
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ben Whitten <ben.whitten@...il.com>
Subject: Re: [PATCH] regmap: prevent noinc writes from clobbering cache

On Wed, Nov 01, 2023 at 04:20:08PM -0400, Ben Wolsieffer wrote:
> On Wed, Nov 01, 2023 at 05:05:39PM +0000, Mark Brown wrote:

> > Could you please add a kunit test for this?

> I started to look into this, but it is not currently possible to test
> noinc behavior with regmap_[raw_]ram. The same bulk write operation is
> used by both incrementing and non-incrementing writes, and the difference
> in behavior is due to how the hardware handles the bulk write to a
> particular register.

> To test this behavior, regmap_raw_ram (raw because it supports bulk
> writes) would have to be told that certain of its registers should
> implement noinc semantics.

> Is this something I should implement?

That would be great, yes - I've just been implementing features in those
map types on an as needed basis as I've been writing tests and I didn't
get round to covering noinc yet.

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