[RFC PATCH 0/2] regmap: add APIs to bypass regmap_field and work with reg_field directly

[Victor Chernyakin]

Working with the existing regmap_field_* APIs requires you to define
a reg_field, then use one of the regmap_field_*_alloc functions to turn
it into a dynamically allocated regmap_field. But reg_field and
regmap_field are practically the same struct; all the *_alloc functions do
is shuffle fields around. So this RFC proposes adding functions that
cut out the middleman and take reg_field directly. Patch 1 adds two
of them: regmap_reg_field_read and regmap_reg_field_write.

Patch 2 ports a driver to use these new functions. The result is
shorter and simpler, since all the code to perform the allocations
and manage the resulting regmap_fields goes away. In theory,
there should also be a performance benefit (we're doing fewer allocations
and have less duplicated state), but I haven't benchmarked it, so take that
with a grain of salt.

If we like this approach, I can post a v2 that adds regmap_reg_field_*
analogs for all the regmap_field_* functions, not just the two you see here.


This is not actually a new idea! Both it and the current *_alloc approach
were suggested as alternatives right when the regmap_field_* APIs were
being added [1]. The *_alloc approach was chosen without much
discussion, but I think (and Patch 2 demonstrates, I hope) that
this approach is the cleaner one.

[1] https://lore.kernel.org/20130604210137.GV31367@xxxxxxxxxxxxx

Victor Chernyakin (2):
  regmap: add regmap_reg_field_* APIs
  iio: accel: msa311: use regmap_reg_field_* functions

 drivers/iio/accel/msa311.c | 297 +++++++++++++------------------------
 include/linux/regmap.h     |  61 ++++++--
 2 files changed, 158 insertions(+), 200 deletions(-)

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2.53.0