| Message ID | m2twgaqp0w.fsf@baylibre.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
Hi Kevin, On Fri, Jul 1, 2016 at 12:40 AM, Kevin Hilman <khilman@baylibre.com> wrote: > Geert Uytterhoeven <geert@linux-m68k.org> writes: >> On Tue, May 17, 2016 at 1:41 PM, Ulf Hansson <ulf.hansson@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.hansson@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 >> 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. > > I have a hunch (without too much digging) that this may be an odd > interaction with the direct_complete stuff since the simple-pm-bus has > no callbacks. > > For kicks, could you add something like the hack below (untested) which > will avoid the direct_complete path, and at least help indicate if > that path is worth investigating further. Thanks! () > diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c > index c5eb46cbf388..63b95fb21510 100644 > --- a/drivers/bus/simple-pm-bus.c > +++ b/drivers/bus/simple-pm-bus.c > @@ -36,6 +36,15 @@ static int simple_pm_bus_remove(struct platform_device *pdev) > return 0; > } > > +static int simple_pm_bus_prepare(struct device *dev) > +{ > + return pm_generic_prepare(dev); This causes an infinite loop, as pm_generic_prepare just calls dev->driver->pm->prepare(dev); > +} > + > +static const struct dev_pm_ops simple_pm_bus_ops = { > + .prepare = simple_pm_bus_prepare, > +}; > + > static const struct of_device_id simple_pm_bus_of_match[] = { > { .compatible = "simple-pm-bus", }, > { /* sentinel */ } > @@ -48,6 +57,7 @@ static struct platform_driver simple_pm_bus_driver = { > .driver = { > .name = "simple-pm-bus", > .of_match_table = simple_pm_bus_of_match, > + .pm = &simple_pm_bus_ops, > }, > }; Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org 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 -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c index c5eb46cbf388..63b95fb21510 100644 --- a/drivers/bus/simple-pm-bus.c +++ b/drivers/bus/simple-pm-bus.c @@ -36,6 +36,15 @@ static int simple_pm_bus_remove(struct platform_device *pdev) return 0; } +static int simple_pm_bus_prepare(struct device *dev) +{ + return pm_generic_prepare(dev); +} + +static const struct dev_pm_ops simple_pm_bus_ops = { + .prepare = simple_pm_bus_prepare, +}; + static const struct of_device_id simple_pm_bus_of_match[] = { { .compatible = "simple-pm-bus", }, { /* sentinel */ } @@ -48,6 +57,7 @@ static struct platform_driver simple_pm_bus_driver = { .driver = { .name = "simple-pm-bus", .of_match_table = simple_pm_bus_of_match, + .pm = &simple_pm_bus_ops, }, };