Merge branch 'cpsw-runtime-pm'

Grygorii Strashko says:

====================
drivers: net: cpsw: improve runtime pm

This series intended to improve runtime PM and allow CPSW to be
RPM suspended when all ethX netdevices are down.

To achieve above goal it is required to relax runtime PM constraints for
Davinci MDIO which blocks CPSW runtime PM now, because Davinci MDIO is always
powered on during probe and powered off only when it's going to be removed.
- Patches 6-11 implement PM runtime autosuspend for Davinci MDIO, but keep it
disabled by default, because Davinci MDIO is integrated in big set of TI devices
and not all of them verified to work correctly with RPM autosuspend enabled:
 expected to work on SoCs where MDIO is defined as part of CPSW in DT
 (cpsw.c DRA7/am57x, am437x, am335x)
The CPSW need to be fixed before RPM suspended can be allowed:
 - Patches 1-5 ensure that CPSW will not cause L3 errors while it is in RPM
   suspended state.

Davinci MDIO RPM autosuspend can be enabled through sysfs:
 echo 100 > /sys/devices/../48484000.ethernet/48485000.mdio/power/autosuspend_delay_ms

Patches 12 - 15: introduce new compatible string "ti,cpsw-mdio" which is used
then to enable RPM for am335x/am437x/dra7 SoCs.

Tested on am335x, am437x, am572x and k2g (on k2g with RPM disabled for Davinci MDIO)
These changes should not affect on errata i877 implementation on DRA7.

Power measurement on am335x GP EVM:
 Without this series:  547.60 mW total SoC power
 With this series + "ifconfig eth0 down": 477.32 mW Total Soc Power

Changes in v2:
- CPSW ethtool interface updated to use .begin()/.complete() callbacks
- kbuild failure fixed
- davinci_mdio DT updated with proper description of allowed compatible strings
  combinations

Link on v1:
 https://lkml.org/lkml/2016/6/15/362
====================

Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>