On Tuesday, June 28, 2016 06:26:36 PM Geert Uytterhoeven wrote: > Hi Ulf, Rafael, > > On Tue, May 17, 2016 at 1:41 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> 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.hansson@xxxxxxxxxx> > > --- > > 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 > 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: > > 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. OK, I've dropped the offending commit from my linux-next branch. Thanks, Rafael
