SSM2602 driver is broken on recent kernels (at least since 4.9). User space applications such as amixer or alsamixer get EIO when attempting to access codec controls via the relevant IOCTLs.

Root cause of these failures is the regcache_hw_init function in drivers/base/regmap/regcache.c, which prevents regmap cache initalization from the reg_defaults_raw element of the regmap_config structure when registers are write only. It also disables the regmap cache entirely when all registers are write only or volatile as is the case for the SSM2602 driver.

Using the reg_defaults element of the regmap_config structure rather than the reg_defaults_raw element to initalize the regmap cache avoids the logic in the regcache_hw_init function entirely. It also makes this driver consistent with other ASoC codec drivers, as this driver was the ONLY codec driver that used the reg_defaults_raw element to initalize the cache.

Tested on Digilent Zybo Z7 development board which has a SSM2603 codec chip connected to a Xilinx Zynq SoC.

Signed-off-by: James Kelly jamespeterkelly@gmail.com --- Sorry I forgot the signature in v1.

sound/soc/codecs/ssm2602.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/sound/soc/codecs/ssm2602.c b/sound/soc/codecs/ssm2602.c index 031e0eabcc1f..501a4e73b185 100644 --- a/sound/soc/codecs/ssm2602.c +++ b/sound/soc/codecs/ssm2602.c @@ -54,10 +54,17 @@ struct ssm2602_priv { * using 2 wire for device control, so we cache them instead. * There is no point in caching the reset register */ -static const u16 ssm2602_reg[SSM2602_CACHEREGNUM] = { - 0x0097, 0x0097, 0x0079, 0x0079, - 0x000a, 0x0008, 0x009f, 0x000a, - 0x0000, 0x0000 +static const struct reg_default ssm2602_reg[SSM2602_CACHEREGNUM] = { + { .reg = 0x00, .def = 0x0097 }, + { .reg = 0x01, .def = 0x0097 }, + { .reg = 0x02, .def = 0x0079 }, + { .reg = 0x03, .def = 0x0079 }, + { .reg = 0x04, .def = 0x000a }, + { .reg = 0x05, .def = 0x0008 }, + { .reg = 0x06, .def = 0x009f }, + { .reg = 0x07, .def = 0x000a }, + { .reg = 0x08, .def = 0x0000 }, + { .reg = 0x09, .def = 0x0000 } };

@@ -621,8 +628,8 @@ const struct regmap_config ssm2602_regmap_config = { .volatile_reg = ssm2602_register_volatile,

.cache_type = REGCACHE_RBTREE, - .reg_defaults_raw = ssm2602_reg, - .num_reg_defaults_raw = ARRAY_SIZE(ssm2602_reg), + .reg_defaults = ssm2602_reg, + .num_reg_defaults = ARRAY_SIZE(ssm2602_reg), }; EXPORT_SYMBOL_GPL(ssm2602_regmap_config);