Re: [PATCH v2 2/2] ASoC: tas2783-sdw: do not cache read-only Controls

[Andrey Golovko <andrey.golovko@gmail.com>]

On Fri, Aug 14, 2026 at 04:13:42PM +0100, Mark Brown wrote:

> Does this work for multibyte reads?  The regmap has val_size set to 8
> but some of the read only registers are multibyte.  For SoundWire
> val_bits doesn't really matter so you should just be able to set that to
> 32.

It does not, thank you.  Twenty of the Controls in the list are wider
than one byte, and with val_bits = 8 the MBQ layer refuses each of them
before anything reaches the bus, so the patch on its own would replace
an answer from the cache with -EINVAL.

The widening is a patch of its own because the calibration write relied
on the old width, so I have sent both as v3 with it in front, against
for-7.3:

  https://lore.kernel.org/linux-sound/20260815112000.4180-1-andrey.golovko@gmail.com/

The cover letter has the list of the multi-byte Controls and what the
two patches were measured to do on the machine here.

One thing I noticed while checking the sizes, unrelated to this series:
FU21 0x10 and UDMPU23 0x06 are in the read-only list but appear nowhere
in tas2783_sdca_mbq_size(), which returns 0 for them, so
tas2783_readable_register() refuses them and they are unreachable
through the regmap in either direction.  Harmless as it stands, nothing
touches them, but the size callback looks incomplete rather than
deliberate.  I can add them, or leave that to TI along with the rest of
the reg_defaults questions I owe them a mail about.

Andrey