[PATCH][SRU Vivid] High CPU usage of kworker/ksoftirqd

[AceLan Kao]

[Impact] 

 * Many new platforms have this kind of issue that CPU loading is always
above 1. We see kworker/ksoftirqd becomes CPU hogger that not only affects
system performance, but also power consumption.

  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
   23 root 20 0 0 0 0 R 71.6 0.0 17:30.13 kworker/2:0
   22 root 20 0 0 0 0 S 28.6 0.0 7:00.61 ksoftirqd/2

 * From upstream we found this commit fix the issue.
9250ae mmc: core: Enable runtime PM management of host devices

[Test Case]

 * This issue could be found on new skylake machines, just boot up by latest
Ubuntu kernel 3.19.0-26 and run top to monitor the CPU usage. It should be
always shows above 1.

 * With the patch, the CPU loading is around 0.3 after idle for 10 mins.

Ulf Hansson (1):
  mmc: core: Enable runtime PM management of host devices

 drivers/mmc/core/core.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

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2.1.4