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Subject[PATCH 11/15] PM / Domains: Do not measure start time for "irq safe" devices

The genpd_start_dev() routine used by pm_genpd_runtime_resume()
to put "irq safe" devices into the full power state measures the
time necessary to "start" the device and updates its PM QoS timing
data if necessary. This may lead to a deadlock if the given device
is a clock source and genpd_start_dev() is invoked from within the
clock source's .enable() routine, which will happen if that routine
uses pm_runtime_get_sync(), for example, to ensure that the device
is operational.

For this reason, introduce a special routine analogous to
genpd_start_dev(), called genpd_start_dev_no_timing(), that doesn't
carry out the time measurement, and make pm_genpd_runtime_resume()
use it instead of genpd_start_dev() to power up "irq safe" devices.

Signed-off-by: Rafael J. Wysocki <>
drivers/base/power/domain.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux/drivers/base/power/domain.c
--- linux.orig/drivers/base/power/domain.c
+++ linux/drivers/base/power/domain.c
@@ -75,6 +75,12 @@ static int genpd_start_dev(struct generi
start_latency_ns, "start");

+static int genpd_start_dev_no_timing(struct generic_pm_domain *genpd,
+ struct device *dev)
+ return GENPD_DEV_CALLBACK(genpd, int, start, dev);
static bool genpd_sd_counter_dec(struct generic_pm_domain *genpd)
bool ret = false;
@@ -626,7 +632,7 @@ static int pm_genpd_runtime_resume(struc

/* If power.irq_safe, the PM domain is never powered off. */
if (dev->power.irq_safe)
- return genpd_start_dev(genpd, dev);
+ return genpd_start_dev_no_timing(genpd, dev);

ret = __pm_genpd_poweron(genpd);

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