soundwire: bus: pm_runtime_request_resume on peripheral attachment

In typical use cases, the peripheral becomes pm_runtime active as a
result of the ALSA/ASoC framework starting up a DAI. The parent/child
hierarchy guarantees that the manager device will be fully resumed
beforehand.

There is however a corner case where the manager device may become
pm_runtime active, but without ALSA/ASoC requesting any functionality
from the peripherals. In this case, the hardware peripheral device
will report as ATTACHED and its initialization routine will be
executed. If this initialization routine initiates any sort of
deferred processing, there is a possibility that the manager could
suspend without the peripheral suspend sequence being invoked: from
the pm_runtime framework perspective, the peripheral is *already*
suspended.

To avoid such disconnects between hardware state and pm_runtime state,
this patch adds an asynchronous pm_request_resume() upon successful
attach/initialization which will result in the proper resume/suspend
sequence to be followed on the peripheral side.

BugLink: https://github.com/thesofproject/linux/issues/3459
Signed-off-by: Pierre-Louis Bossart <[email protected]>
Reviewed-by: Ranjani Sridharan <[email protected]>
Reviewed-by: Rander Wang <[email protected]>
Signed-off-by: Bard Liao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

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