On 28 June 2016 at 18:26, Geert Uytterhoeven <ge...@linux-m68k.org> wrote: > Hi Ulf, Rafael, > > On Tue, May 17, 2016 at 1:41 PM, Ulf Hansson <ulf.hans...@linaro.org> wrote: >> When the pm_runtime_force_suspend|resume() helpers were invented, we still >> had CONFIG_PM_RUNTIME and CONFIG_PM_SLEEP as separate Kconfig options. >> >> To make sure these helpers worked for all combinations and without >> introducing too much of complexity, the device was always resumed in >> pm_runtime_force_resume(). >> >> More precisely, when CONFIG_PM_SLEEP was set and CONFIG_PM_RUNTIME was >> unset, we needed to resume the device as the subsystem/driver couldn't >> rely on using runtime PM to do it. >> >> As the CONFIG_PM_RUNTIME option was merged into CONFIG_PM a while ago, it >> removed this combination, of using CONFIG_PM_SLEEP without the earlier >> CONFIG_PM_RUNTIME. >> >> For this reason we can now rely on the subsystem/driver to use runtime PM >> to resume the device, instead of forcing that to be done in all cases. In >> other words, let's defer this to a later point when it's actually needed. >> >> Signed-off-by: Ulf Hansson <ulf.hans...@linaro.org> >> --- >> drivers/base/power/runtime.c | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c >> index 09e4eb1..1db7b46 100644 >> --- a/drivers/base/power/runtime.c >> +++ b/drivers/base/power/runtime.c >> @@ -1509,6 +1509,17 @@ int pm_runtime_force_resume(struct device *dev) >> if (!pm_runtime_status_suspended(dev)) >> goto out; >> >> + /* >> + * The PM core increases the runtime PM usage count in the system PM >> + * prepare phase. If the count is greather than 1 at this point, >> someone >> + * else has also increased it. In that case, invoke the runtime >> resume >> + * callback for the device as that is likely what is expected. In >> other >> + * case we trust the subsystem/driver to runtime resume the device >> when >> + * it's actually needed. >> + */ >> + if (atomic_read(&dev->power.usage_count) < 2) >> + goto out; >> + >> ret = pm_runtime_set_active(dev); >> if (ret) >> goto out; > > This patch (commit eb13a0a1b6d5d5c2 in pm/linux-next) breaks resume on
Thanks for reporting! > sh73a0/kzm9g and r8a73a4/ape6evm. On these boards, the Ethernet controller is > a > child of a local bus (bsc), whose clock (zb) is controlled through pm_clk and > simple-pm-bus, cfr. > > arch/arm/boot/dts/r8a73a4-ape6evm.dts > arch/arm/boot/dts/r8a73a4.dtsi > arch/arm/boot/dts/sh73a0-kzm9g.dts > arch/arm/boot/dts/sh73a0.dtsi > > During resume, the bus clock is not enabled, causing an imprecise abort > when accessing the Ethernet controller's registers. With some debug code > added: I was looking into this in some more detail. As you are stating that Ethernet device is a child device to the local bus device, I would have expected that the pm_runtime_get_sync() invoked during ->probe() in the Ethernet driver should cause its parent device (the bus device) to be "forced" resumed. That's because the pm_runtime_get_sync() should trigger an increased usage count of the parent device. Later, when pm_runtime_force_resume() validates the count for the bus device, it should be 2 and thus it should lead to that it decides to *not* defer the resume of the device. Apparently this isn't happening for some reason... Perhaps there's a pm_suspend_ignore_children() set for the parent? Or perhaps the parent/child relationship isn't set up correctly? > > PM: Syncing filesystems ... done. > PM: Preparing system for sleep (mem) > Freezing user space processes ... (elapsed 0.001 seconds) done. > Double checking all user space processes after OOM killer > disable... (elapsed 0.000 seconds) > Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. > PM: Suspending system (mem) > smsc911x: smsc911x_suspend > simple-pm-bus fec10000.bus: simple_pm_bus_suspend > PM: suspend of devices complete after 21.484 msecs > PM: suspend devices took 0.030 seconds > PM: late suspend of devices complete after 0.488 msecs > cpg_div6_clock_disable: zb > rmobile_pd_power_down: a3sp > PM: noirq suspend of devices complete after 8.300 msecs > Disabling non-boot CPUs ... > CPU1: shutdown > > PM: early resume of devices complete after 0.488 msecs > simple-pm-bus fec10000.bus: simple_pm_bus_resume > smsc911x: smsc911x_resume > Unhandled fault: imprecise external abort (0x1406) at 0xb6f40068 > pgd = deedc000 > [b6f40068] *pgd=5f774831, *pte=4087659f, *ppte=40876e7e > Internal error: : 1406 [#1] SMP ARM > Modules linked in: > CPU: 0 PID: 1062 Comm: s2ram Not tainted > 4.7.0-rc5-kzm9g-00391-g87777f5105e9303a-dirty #765 > Hardware name: Generic SH73A0 (Flattened Device Tree) > task: dedc0840 ti: deee6000 task.ti: deee6000 > PC is at __smsc911x_reg_read+0x1c/0x60 > LR is at smsc911x_resume+0x78/0xd0 > > After reverting this patch, resume succeeds again, as the zb clock is enabled > first: > > PM: Syncing filesystems ... done. > PM: Preparing system for sleep (mem) > Freezing user space processes ... (elapsed 0.001 seconds) done. > Double checking all user space processes after OOM killer > disable... (elapsed 0.000 seconds) > Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. > PM: Suspending system (mem) > smsc911x: smsc911x_suspend > simple-pm-bus fec10000.bus: simple_pm_bus_suspend > PM: suspend of devices complete after 22.460 msecs > PM: suspend devices took 0.030 seconds > PM: late suspend of devices complete after 0.488 msecs > cpg_div6_clock_disable: zb > rmobile_pd_power_down: a3sp > PM: noirq suspend of devices complete after 8.300 msecs > Disabling non-boot CPUs ... > CPU1: shutdown > > Enabling non-boot CPUs ... > CPU1 is up > rmobile_pd_power_up: a3sp > rmobile_pd_power_up: a4mp > a4mp: Power on, 0x00000100 -> PSTR = 0x007b3133 > cpg_div6_clock_enable: zb > PM: noirq resume of devices complete after 92.773 msecs > PM: early resume of devices complete after 0.488 msecs > simple-pm-bus fec10000.bus: simple_pm_bus_resume > smsc911x: smsc911x_resume > PM: resume of devices complete after 28.564 msecs > PM: resume devices took 0.040 seconds > PM: Finishing wakeup. > Restarting tasks ... > rmobile_pd_power_down: a4mp > a4mp: Power off, 0x00000100 -> PSTR = 0x007b3033 > done. Thanks for the detailed explanation of what is happening! Unless we can fix this in the Ethernet driver/local bus, I have some ideas of how we could change genpd, to still allow $subject patch to be applied. Although I will wait a day or two before I propose something. In the meantime I will also try to collect some more information. Thanks! Kind regards Uffe
