commit c8158819d506a8aedeca53c52dfb709a0aabe011
author Lin Ming <ming.m.lin@intel.com> Sat Mar 23 11:42:27 2013 +0800
committer Jens Axboe <axboe@kernel.dk> Fri Mar 22 22:22:15 2013 -0600
tree acabca463a1898931cd325c415a51a819eabee00
parent 6c9546675864f51506af69eca388e5d922942c56

block: implement runtime pm strategy

When a request is added:
    If device is suspended or is suspending and the request is not a
    PM request, resume the device.

When the last request finishes:
    Call pm_runtime_mark_last_busy().

When pick a request:
    If device is resuming/suspending, then only PM request is allowed
    to go.

The idea and API is designed by Alan Stern and described here:
http://marc.info/?l=linux-scsi&m=133727953625963&w=2

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jens Axboe <axboe@kernel.dk>