On Mon, Oct 16, 2017 at 10:36 AM, Geert Uytterhoeven
<geert+renesas@xxxxxxxxx> wrote:
> 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 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. in the
> absence of commit fbf3d034f2ff6264 ("ravb: add workaround for clock when
> resuming with WoL enabled"), 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 clocks that were disabled by clk_disable_unused() may
> have been re-enabled, wasting power.
>
> This patch series fixes these issues by restoring clock registers during
> system resume. Note that 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.
>
> Changes compared to v2:
> - Drop RFC state,
> - Add Tested-by,
> - Add build and runtime dependencies on PM_SLEEP and PSCI.
>
> Changes compared to v1 (more details in the individual patches):
> - Save module clock registers in suspend_noirq instead of constantly
> updating shadow registers,
> - Restore all module clocks under our control, not just the ones we ever
> changed,
> - Also restore DIV6, SDHI, and R clocks, thus covering all supported
> programmable core clocks on R-Car Gen3.
>
> This series is against the clk-renesas branch of my renesas-drivers git
> repository at
> git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git.
> For your convenience, this series is also available in the
> topic/cpg-mssr-suspend-resume-v3 branch of the same repository.
>
> This has been tested on Salvator-X with R-Car H3 ES1.0 and M3-W ES1.0,
> and on Salvator-XS with R-Car H3 ES2.0 (the latter also needs "[PATCH
> 0/4] ravb: Add PHY reset support",
> https://www.spinics.net/lists/netdev/msg457308.html), and
> regression-tested on various other Renesas arm32 boards not using PSCI.
>
> I plan to queue this up in clk-renesas-for-v4.15.
Done.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
