When there are more than one device in a PM domain these will obviously
be probed at different times. Depending on timing and the implemented
support for runtime PM in a driver/subsystem, genpd may be advised to
power off a PM domain after a successful probe sequence.
Ideally we should have relied on the driver/subsystem, through runtime
PM, to bring their device's PM domain into powered state prior doing
probing if such requirement exist.
Since this is not a common practice by drivers/subsystems, enforcing
such a change doesn't seem viable.
Instead, let's improve the situation, by preventing genpd from powering
off any of the PM domains until late_init. At that point genpd already
tries to power off unused PM domains, so it seems like a decent match.
Cases which can't be covered within the window of until late_init needs
to be adressed separately and likely through a more common long term
solution.
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
drivers/base/power/domain.c | 17 ++++++++++++++++-
include/linux/pm_domain.h | 1 +
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index cfb76e8..3dbadfd 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -451,10 +451,12 @@ static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
* (2) The domain is waiting for its master to power up.
* (3) One of the domain's devices is being resumed right now.
* (4) System suspend is in progress.
+ * (5) late_init hasn't completed to allow it.
*/
if (genpd->status == GPD_STATE_POWER_OFF
|| genpd->status == GPD_STATE_WAIT_MASTER
- || genpd->resume_count > 0 || genpd->prepared_count > 0)
+ || genpd->resume_count > 0 || genpd->prepared_count > 0
+ || genpd->keep_power)
return 0;
if (atomic_read(&genpd->sd_count) > 0)
@@ -724,6 +726,18 @@ void pm_genpd_poweroff_unused(void)
static int __init genpd_poweroff_unused(void)
{
+ struct generic_pm_domain *genpd;
+
+ mutex_lock(&gpd_list_lock);
+
+ list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
+ genpd_acquire_lock(genpd);
+ genpd->keep_power = false;
+ genpd_release_lock(genpd);
+ }
+
+ mutex_unlock(&gpd_list_lock);
+
pm_genpd_poweroff_unused();
return 0;
}
@@ -1854,6 +1868,7 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
genpd->status = GPD_STATE_ACTIVE;
init_waitqueue_head(&genpd->status_wait_queue);
genpd->poweroff_task = NULL;
+ genpd->keep_power = true;
genpd->resume_count = 0;
genpd->device_count = 0;
genpd->max_off_time_ns = -1;
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index ad4aa87..d87ef6a 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -58,6 +58,7 @@ struct generic_pm_domain {
enum gpd_status status; /* Current state of the domain */
wait_queue_head_t status_wait_queue;
struct task_struct *poweroff_task; /* Powering off task */
+ bool keep_power; /* Flag to keep power until late_init */
unsigned int resume_count; /* Number of devices being resumed */
unsigned int device_count; /* Number of devices */
unsigned int suspended_count; /* System suspend device counter */
--
1.9.1
--
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