linux-kernel - Re: [PATCH] regmap: support regmap_field

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Date:   Tue, 19 Jul 2022 13:53:39 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH] regmap: support regmap_field_write() on non-readable
 fields

On Tue, Jul 19, 2022 at 02:14:46PM +0200, Krzysztof Kozlowski wrote:

> Extend regmap_field_write() and regmap_field_force_write() to check if
> register is readable and only then perform an update.  In the other
> case, it is expected that mask of field covers entire register thus a
> full write is allowed.

The other possible assumption there would be that the other bits are
write as zero - that's not 100% safe but does make sense if for example
the fields are being used to capture acknowledgement flags moving
around.  That's not incompatible with doing this of course, we can
always relax things later.

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