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During PSCI system suspend, R-Car Gen3 SoCs are powered down, and their
clock register state is lost. Note that as the boot loader skips most
initialization after system resume, clock register state differs from
the state encountered during normal system boot, too.
Hence after s2ram, some operations may fail because module clocks are
disabled, while drivers expect them to be still enabled. E.g. EtherAVB
fails when Wake-on-LAN has been enabled using "ethtool -s eth0 wol g":
ravb e6800000.ethernet eth0: failed to switch device to config mode
ravb e6800000.ethernet eth0: device will be stopped after h/w processes are done.
ravb e6800000.ethernet eth0: failed to switch device to config
PM: Device e6800000.ethernet failed to resume: error -110
In addition, some module clocks that were disabled by
clk_disable_unused() may have been re-enabled, wasting power.
To fix this, restore all bits of the SMSTPCR registers that represent
clocks under control of Linux.
Notes:
- While this fixes EtherAVB operation after resume from s2ram,
EtherAVB cannot be used as an actual wake-up source from s2ram, only
from s2idle, due to PSCI limitations,
- To avoid overhead on platforms not needing it, the suspend/resume
code has a build time dependency on sleep and PSCI support, and a
runtime dependency on PSCI.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.