libata: async resume

Improve overall system resume time by making libata link recovery
actions asynchronous relative to other resume events.

Link resume operations are performed using the scsi_eh thread, so
commands, particularly the sd resume start/stop command, will be held
off until the device exits error handling.  Libata already flushes eh
with ata_port_wait_eh() in the port teardown paths, so there are no
concerns with async operation colliding with the end-of-life of the
ata_port object.  Also, libata-core is already careful to flush
in-flight pm operations before another round of pm starts on the given
ata_port.

Reference: https://01.org/suspendresume/blogs/tebrandt/2013/hard-disk-resume-optimization-simpler-approach

Cc: Len Brown <[email protected]>
Cc: Phillip Susi <[email protected]>
Cc: Alan Stern <[email protected]>
Signed-off-by: Todd Brandt <[email protected]>
[djbw: rebase on cleanup patch, changelog wordsmithing]
Signed-off-by: Dan Williams <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

0 files changed, 0 insertions, 0 deletions