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Message-Id: <201107311949.58790.rjw@sisk.pl>
Date: Sun, 31 Jul 2011 19:49:58 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Magnus Damm <magnus.damm@...il.com>, linux-sh@...r.kernel.org
Subject: [PATCH 5/9] PM / Domains: Add "wait for parent" status for generic PM domains
From: Rafael J. Wysocki <rjw@...k.pl>
The next patch will make it possible for a generic PM domain to have
multiple parents (i.e. multiple PM domains it depends on). To
prepare for that change it is necessary to change pm_genpd_poweron()
so that it doesn't jump to the start label after running itself
recursively for the parent domain. For this purpose, introduce a new
PM domain status value GPD_STATE_WAIT_PARENT that will be set by
pm_genpd_poweron() before calling itself recursively for the parent
domain and modify the code in drivers/base/power/domain.c so that
the GPD_STATE_WAIT_PARENT status is guaranteed to be preserved during
the execution of pm_genpd_poweron() for the parent.
This change also causes pm_genpd_add_subdomain() and
pm_genpd_remove_subdomain() to wait for started pm_genpd_poweron() to
complete and allows pm_genpd_runtime_resume() to avoid dropping the
lock after powering on the PM domain.
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
drivers/base/power/domain.c | 90 +++++++++++++++++++++++++++++---------------
include/linux/pm_domain.h | 1
2 files changed, 61 insertions(+), 30 deletions(-)
Index: linux-2.6/include/linux/pm_domain.h
===================================================================
--- linux-2.6.orig/include/linux/pm_domain.h
+++ linux-2.6/include/linux/pm_domain.h
@@ -13,6 +13,7 @@
enum gpd_status {
GPD_STATE_ACTIVE = 0, /* PM domain is active */
+ GPD_STATE_WAIT_PARENT, /* PM domain's parent is being waited for */
GPD_STATE_BUSY, /* Something is happening to the PM domain */
GPD_STATE_REPEAT, /* Power off in progress, to be repeated */
GPD_STATE_POWER_OFF, /* PM domain is off */
Index: linux-2.6/drivers/base/power/domain.c
===================================================================
--- linux-2.6.orig/drivers/base/power/domain.c
+++ linux-2.6/drivers/base/power/domain.c
@@ -81,45 +81,59 @@ static void genpd_set_active(struct gene
}
/**
- * pm_genpd_poweron - Restore power to a given PM domain and its parents.
+ * __pm_genpd_poweron - Restore power to a given PM domain and its parents.
* @genpd: PM domain to power up.
*
* Restore power to @genpd and all of its parents so that it is possible to
* resume a device belonging to it.
*/
-int pm_genpd_poweron(struct generic_pm_domain *genpd)
+int __pm_genpd_poweron(struct generic_pm_domain *genpd)
+ __releases(&genpd->lock) __acquires(&genpd->lock)
{
- struct generic_pm_domain *parent;
+ DEFINE_WAIT(wait);
int ret = 0;
- mutex_lock(&genpd->lock);
+ /* If the domain's parent is being waited for, we have to wait too. */
+ for (;;) {
+ prepare_to_wait(&genpd->status_wait_queue, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (genpd->status != GPD_STATE_WAIT_PARENT)
+ break;
+ mutex_unlock(&genpd->lock);
- parent = genpd->parent;
+ schedule();
+
+ mutex_lock(&genpd->lock);
+ }
+ finish_wait(&genpd->status_wait_queue, &wait);
- start:
if (genpd->status == GPD_STATE_ACTIVE
|| (genpd->prepared_count > 0 && genpd->suspend_power_off))
- goto out;
+ return 0;
if (genpd->status != GPD_STATE_POWER_OFF) {
genpd_set_active(genpd);
- goto out;
+ return 0;
}
- if (parent) {
- genpd_sd_counter_inc(parent);
+ if (genpd->parent) {
+ genpd_sd_counter_inc(genpd->parent);
+ genpd->status = GPD_STATE_WAIT_PARENT;
mutex_unlock(&genpd->lock);
- ret = pm_genpd_poweron(parent);
+ ret = pm_genpd_poweron(genpd->parent);
mutex_lock(&genpd->lock);
+ /*
+ * The "wait for parent" status is guaranteed not to change
+ * while the parent is powering on.
+ */
+ genpd->status = GPD_STATE_POWER_OFF;
+ wake_up_all(&genpd->status_wait_queue);
if (ret)
goto err;
-
- parent = NULL;
- goto start;
}
if (genpd->power_on) {
@@ -130,16 +144,27 @@ int pm_genpd_poweron(struct generic_pm_d
genpd_set_active(genpd);
- out:
- mutex_unlock(&genpd->lock);
-
- return ret;
+ return 0;
err:
if (genpd->parent)
genpd_sd_counter_dec(genpd->parent);
- goto out;
+ return ret;
+}
+
+/**
+ * pm_genpd_poweron - Restore power to a given PM domain and its parents.
+ * @genpd: PM domain to power up.
+ */
+int pm_genpd_poweron(struct generic_pm_domain *genpd)
+{
+ int ret;
+
+ mutex_lock(&genpd->lock);
+ ret = __pm_genpd_poweron(genpd);
+ mutex_unlock(&genpd->lock);
+ return ret;
}
#endif /* CONFIG_PM */
@@ -225,7 +250,8 @@ static void __pm_genpd_restore_device(st
*/
static bool genpd_abort_poweroff(struct generic_pm_domain *genpd)
{
- return genpd->status == GPD_STATE_ACTIVE || genpd->resume_count > 0;
+ return genpd->status == GPD_STATE_WAIT_PARENT
+ || genpd->status == GPD_STATE_ACTIVE || genpd->resume_count > 0;
}
/**
@@ -261,11 +287,13 @@ static int pm_genpd_poweroff(struct gene
/*
* Do not try to power off the domain in the following situations:
* (1) The domain is already in the "power off" state.
- * (2) System suspend is in progress.
+ * (2) The domain is waiting for its parent to power up.
* (3) One of the domain's devices is being resumed right now.
+ * (4) System suspend is in progress.
*/
- if (genpd->status == GPD_STATE_POWER_OFF || genpd->prepared_count > 0
- || genpd->resume_count > 0)
+ if (genpd->status == GPD_STATE_POWER_OFF
+ || genpd->status == GPD_STATE_WAIT_PARENT
+ || genpd->resume_count > 0 || genpd->prepared_count > 0)
return 0;
if (atomic_read(&genpd->sd_count) > 0)
@@ -299,14 +327,15 @@ static int pm_genpd_poweroff(struct gene
list_for_each_entry_reverse(dle, &genpd->dev_list, node) {
ret = atomic_read(&genpd->sd_count) == 0 ?
__pm_genpd_save_device(dle, genpd) : -EBUSY;
+
+ if (genpd_abort_poweroff(genpd))
+ goto out;
+
if (ret) {
genpd_set_active(genpd);
goto out;
}
- if (genpd_abort_poweroff(genpd))
- goto out;
-
if (genpd->status == GPD_STATE_REPEAT) {
genpd->poweroff_task = NULL;
goto start;
@@ -432,11 +461,12 @@ static int pm_genpd_runtime_resume(struc
if (IS_ERR(genpd))
return -EINVAL;
- ret = pm_genpd_poweron(genpd);
- if (ret)
- return ret;
-
mutex_lock(&genpd->lock);
+ ret = __pm_genpd_poweron(genpd);
+ if (ret) {
+ mutex_unlock(&genpd->lock);
+ return ret;
+ }
genpd->status = GPD_STATE_BUSY;
genpd->resume_count++;
for (;;) {
--
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