[PATCH 2/9] PM / Domains: Enable genpd to support ->get|put() callbacks

[xiechao_linux@163.com (Chao)]

At 2015-03-13 23:43:42, "Ulf Hansson" <ulf.hansson@linaro.org> wrote:
>To provide users control over whether the power should be maintained,
>implement the ->get|put() callbacks for genpd's PM domain.
>
>A usage count variable keeps track of the number of users. A positive
>value tells genpd to keep supplying power and also to power up if it's
>the first user.
>
>Once the usage count reaches zero, genpd tries to power off its PM
>domain.
>
>Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>---
> drivers/base/power/domain.c | 26 +++++++++++++++++++++++++-
> include/linux/pm_domain.h   |  1 +
> 2 files changed, 26 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
>index 45937f8..7314459 100644
>--- a/drivers/base/power/domain.c
>+++ b/drivers/base/power/domain.c
>@@ -495,10 +495,12 @@ 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) The usage_count > 0, since it tells us to stay powered.
> 	 */
> 	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
>+	    || atomic_read(&genpd->usage_count) > 0)
> 		return 0;
> 
> 	if (atomic_read(&genpd->sd_count) > 0)
>@@ -1377,6 +1379,25 @@ EXPORT_SYMBOL_GPL(pm_genpd_syscore_poweron);
> 
> #endif /* CONFIG_PM_SLEEP */
> 
>+static int genpd_get(struct dev_pm_domain *domain)
>+{
>+	struct generic_pm_domain *genpd = pd_to_genpd(domain);
>+
>+	atomic_inc(&genpd->usage_count);
>+
>+	return pm_genpd_poweron(genpd);
>+}
>+
>+static void genpd_put(struct dev_pm_domain *domain)
>+{
>+	struct generic_pm_domain *genpd = pd_to_genpd(domain);
>+
>+	if (!atomic_dec_and_test(&genpd->usage_count))
>+		return;
>+
>+	genpd_queue_power_off_work(genpd);
>+}
>+
> static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
> 					struct generic_pm_domain *genpd,
> 					struct gpd_timing_data *td)
>@@ -1874,10 +1895,13 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
> 	genpd->status = is_off ? GPD_STATE_POWER_OFF : GPD_STATE_ACTIVE;
> 	init_waitqueue_head(&genpd->status_wait_queue);
> 	genpd->poweroff_task = NULL;
>+	atomic_set(&genpd->usage_count, 0);
> 	genpd->resume_count = 0;
> 	genpd->device_count = 0;
> 	genpd->max_off_time_ns = -1;
> 	genpd->max_off_time_changed = true;
>+	genpd->domain.get = genpd_get;
>+	genpd->domain.put = genpd_put;


What is the difference that call pm_runtime_get/put when probe device?
When the device is attached to the power domain.
We can still use pm_runtime_get/put to power on/shutdown the power domain and make the device probed correctly with power domain on.

>-- 
>1.9.1
>
>
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