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bd941dfa |
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30-Mar-2022 |
Rikard Falkeborn <rikard.falkeborn@gmail.com> |
regmap: Constify static regmap_bus structs
The only usage of these is to pass their address to __regmap_init() or
__devm_regmap_init(), both which takes pointers to const struct
regmap_bus. Make them const to allow the compiler to put them in
read-only memory.
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20220330214110.36337-1-rikard.falkeborn@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
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| #
fb5103f9 |
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03-Nov-2020 |
Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> |
regmap/SoundWire: sdw: add support for SoundWire 1.2 MBQ
The SoundWire 1.1 specification only allowed for reads and writes of
bytes. The SoundWire 1.2 specification adds a new capability to
transfer "Multi-Byte Quantities" (MBQ) across the bus. The transfers
still happens one-byte-at-a-time, but the update is atomic.
For example when writing a 16-bit volume, the first byte transferred
is only taken into account when the second byte is successfully
transferred.
The mechanism is symmetrical for read and writes:
- On a read, the address of the last byte to be read is modified by
setting the MBQ bit
- On a write, the address of all but the last byte to be written are
modified by setting the MBQ bit. The address for the last byte relies
on the MBQ bit being cleared.
The current definitions for MBQ-based controls in the SDCA draft
standard are limited to 16 bits for volumes, so for now this is the
only supported format. An update will be provided if and when support
for 24-bit and 32-bit values is specified by the SDCA standard.
One possible objection is that this code could have been handled with
regmap-sdw.c. However this is a new spec addition not handled by every
SoundWire 1.1 and non-SDCA device, so there's no reason to load code
that will never be used.
Also in practice it's extremely unlikely that CONFIG_REGMAP would not
be selected with CONFIG_REGMAP_MBQ selected. However there's no
functional dependency between the two modules so they can be selected
separately.
Reviewed-by: Rander Wang <rander.wang@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20201103172226.4278-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
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