According to SoundWire Specification Version 1.2. "A Data Port number X (in the range 0-14) which supports only one value of WordLength may implement the WordLength field in the DPX_BlockCtrl1 Register as Read-Only, returning the fixed value of WordLength in response to reads."
As WSA881x interfaces in PDM mode making the only field "WordLength" in DPX_BlockCtrl1" fixed and read-only. Behaviour of writing to this register on WSA881x soundwire slave with Qualcomm Soundwire Controller is throwing up an error. Not sure how other controllers deal with writing to readonly registers, but this patch provides a way to avoid writes to DPN_BlockCtrl1 register by providing a read_only_wordlength flag in struct sdw_dpn_prop
Srinivas Kandagatla (2): soundwire: stream: Add read_only_wordlength flag to port properties ASoC: wsa881x: mark read_only_wordlength flag
drivers/soundwire/stream.c | 16 +++++++++------- include/linux/soundwire/sdw.h | 2 ++ sound/soc/codecs/wsa881x.c | 4 ++++ 3 files changed, 15 insertions(+), 7 deletions(-)