As per USB and UAC2 specs, asynchronous audio sink endpoint
requires explicit synchronization mechanism (Isochronous
Feedback Endpoint)
Implement feedback companion endpoint for ISO OUT endpoint
This patch adds all required infrastructure and USB requests
handling for feedback endpoint. Syncrhonization itself is
still dummy (feedback ep always reports 'nomimal frequency'
e.g. no adjustement is needed). This satisfies hosts that
require feedback endpoint (like Win10) and poll it periodically
Actual synchronization mechanism should be implemented
separately
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20210603220104.1216001-2-jbrunet@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
24f779dac8