runtime_usage of sound card has been observed to grow without bound.
For example:
$ cat /sys/devices/platform/sound/power/runtime_usage
46
$ sox -n -t s16 -r 48000 -c 2 - synth 1 sine 440 vol 0.1 | \
  aplay -q -D hw:0,0 -f S16_LE -r 48000 -c 2
$ cat /sys/devices/platform/sound/power/runtime_usage
52

Commit 4e872a46 ("ASoC: dapm: Don't force card bias level to be
updated") stops to force update bias_level on card.  If card doesn't
provide set_bias_level callback, the snd_soc_dapm_set_bias_level()
is equivalent to NOP for card device.

As a result, dapm_pre_sequence_async() doesn't change the bias_level of
card device correctly.  Thus, pm_runtime_get_sync() would be called in
dapm_pre_sequence_async() without symmetric pm_runtime_put() in
dapm_post_sequence_async().

Don't call pm_runtime_* on card device.
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200724070731.451377-1-tzungbi@google.comSigned-off-by: Mark Brown <broonie@kernel.org>