Hello all,

when I try to read the register values of a i2c ASoC codec through
debugfs, (eg: cat /sys/kernel/debug/regmap/1-001a/registers)
I am getting an WARN_ON at drivers/base/regmap/regmap-debugfs.c:151.
Please see attached dmesg.txt for details.

I did some debugging and found that regmap_readable(), at regmap-
debugfs.c:109, returns "false" for all registers, hence the 
debugfs_off_cache list remains empty and we get an warning in line 151.

Reverting commit 4191f1979 "regmap: if format_write is used, declare
all registers as "unreadable"" fixed the issue.

Regards,
Sergej