Public bug reported:

[Impact]
BT fails to load firmware after S3. On my system it's atheros' chip, but the 
same issue can be seen with broadcom's chip, too.
   [542.6274] WARNING: CPU: 0 PID: 20729 at 
/build/linux-MD8jsN/linux-4.4.0/drivers/base/firmware_class.c:1148 
_request_firmware+0x7c2/0xaf0()

The root cause of this issue is request_firmware() is being called at
the wrong time.

[Fix]
The fix is from this old thread[1], but the patch didn't be accepted by the 
maintainer.
It prevents the work queue from being re-created and calls request_firmware() 
immediately before usermodehelper is fully resumed. Making the workqueue 
freezable preserves the delay and will postpone the firmware loading time.

[Test Case]
Verified on the machine has this issue, and confirm this patch works.

[Regression Potential]
>From what I can see, I think this change should be safe, and after 240 times 
>S3 test, the system and BT functions are still working.

1. http://lists.openwall.net/netdev/2015/05/06/3

** Affects: linux (Ubuntu)
     Importance: Undecided
     Assignee: AceLan Kao (acelankao)
         Status: In Progress

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https://bugs.launchpad.net/bugs/1706833

Title:
  atheros bt failed after S3

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