[BUG ?] regmap: debugfs: WARN_ON at regmap-debugfs.c:151

[Sergej Sawazki]

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
[  507.037105] ------------[ cut here ]------------
[  507.037173] WARNING: CPU: 0 PID: 2609 at drivers/base/regmap/regmap-debugfs.c:151 regmap_debugfs_get_dump_start.part.0+0x210/0x26c()
[  507.037188] Modules linked in: 8192cu snd_soc_wm8741 regmap_spi snd_soc_bcm2708_i2s regmap_mmio snd_soc_tau_dac
snd_soc_core snd_compress snd_pcm_dmaengine snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_midi snd_rawmidi snd_seq_oss snd_seq_midi_ev
ent snd_seq snd_seq_device snd_timer clk_si5351 regmap_i2c snd i2c_bcm2708 sg uio_pdrv_genirq uio
[  507.037320] CPU: 0 PID: 2609 Comm: cat Tainted: G        W      3.18.7-tau-dac-00032-g604bbbc-dirty #54
[  507.037388] [<c00158e4>] (unwind_backtrace) from [<c0012c40>] (show_stack+0x20/0x24)
[  507.037438] [<c0012c40>] (show_stack) from [<c0554008>] (dump_stack+0x20/0x28)
[  507.037480] [<c0554008>] (dump_stack) from [<c0023608>] (warn_slowpath_common+0x7c/0x9c)
[  507.037511] [<c0023608>] (warn_slowpath_common) from [<c0023654>] (warn_slowpath_null+0x2c/0x34)
[  507.037539] [<c0023654>] (warn_slowpath_null) from [<c0375a30>] (regmap_debugfs_get_dump_start.part.0+0x210/0x26c)
[  507.037569] [<c0375a30>] (regmap_debugfs_get_dump_start.part.0) from [<c0375b30>] (regmap_reg_ranges_read_file+0xa4/0x280)
[  507.037609] [<c0375b30>] (regmap_reg_ranges_read_file) from [<c0136a0c>] (vfs_read+0x98/0x184)
[  507.037639] [<c0136a0c>] (vfs_read) from [<c0136b44>] (SyS_read+0x4c/0x98)
[  507.037668] [<c0136b44>] (SyS_read) from [<c000f580>] (ret_fast_syscall+0x0/0x48)
[  507.037684] ---[ end trace b52574e72eb4e3d1 ]---