Re: Question: regmap_field_write() - why using update?

[Mark Brown <broonie@kernel.org>]

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On Thu, Jul 14, 2022 at 05:01:29PM +0200, Krzysztof Kozlowski wrote:

> I am converting my driver using MMIO to regmap from readl/writel and to
> my surprise I found that regmap_field_write() does not behave the same
> as regmap_write(). I would expect that they are the same, except one
> operates on fields.

> However regmap_field_write() uses an update method [1] which means it
> reads and performs update. regmap_write() simply writes without a read.

> I find it inconsistent and a bit confusing. Any reasons for such
> behavior so I won't send a patch which breaks 100 of devices?

How would you propose to write to a field without reading the rest of
the bits in the register?  Otherwise you'd be doing a full register
write rather than just a write to the specific field.

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