It is possible that during system boot when there multiple devices
attempting simultaneous initialization on a slow control bus the
download of firmware and tuning data may take a user perceivable amount
of time (a slow I2C bus with 4 amps this work could take over 2
seconds).

Adopt a pattern used in the ASoC driver and perform this activity in a
background thread so that interactive performance is not impaired. The
system_long_wq is a parallel workqueue and driver instances will perform
their firmware downloads in parallel to make best use of available bus
bandwidth.
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://lore.kernel.org/20240618130011.62860-1-simont@opensource.cirrus.comSigned-off-by: Takashi Iwai <tiwai@suse.de>