On 8 October 2012 03:31, Rafael J. Wysocki rjw@sisk.pl wrote:

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On Thursday 04 of October 2012 14:58:33 Rajagopal Venkat wrote:

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Add devfreq suspend/resume apis for devfreq users. This patch supports suspend and resume of devfreq load monitoring, required for devices which can idle.

Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org Acked-by: MyungJoo Ham myungjoo.ham@samsung.com

Well, I wonder if this may be tied in to the runtime PM framework, so that, for example, pm_runtime_suspend() will automatically suspend devfreq on success (and the runtime resume of the device will resume devfreq)?

That's a good idea. If you agree, we can handle this as separate patch on top this patchset.

I guess implementing the idea may be not so obvious; thus, seperating the patchset would be appropriate.

When we implement the idea, we may need to implement at the pm_runtime core. Because devfreq->dev is a child of the target dev, not a parent, runtime-pm event of the target dev does not automatically invoke a cascaded action on the devfreq->dev.

Maybe either 1) capability to allow a child to monitor the power state of a parent (I remember Inki Dae once suggested to add notifiers at runtime-pm, but it seems to be not merged) or 2) letting runtime-pm be aware of devfreq (doesn't feel alright with this??) is required?

...

Rafael

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---

drivers/devfreq/devfreq.c | 28 ++++++++++++++++++++++++++++ drivers/devfreq/governor.h | 2 ++ drivers/devfreq/governor_simpleondemand.c | 9 +++++++++ include/linux/devfreq.h | 12 ++++++++++++ 4 files changed, 51 insertions(+)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 41a4099..63e075e 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -428,6 +428,34 @@ int devfreq_remove_device(struct devfreq *devfreq) } EXPORT_SYMBOL(devfreq_remove_device);

+/**

• • devfreq_suspend_device() - Suspend devfreq of a device.
• • @devfreq the devfreq instance to be suspended
• */

+int devfreq_suspend_device(struct devfreq *devfreq) +{

• if (!devfreq)
  

•         return -EINVAL;
  

• return devfreq->governor->event_handler(devfreq,
  

•                         DEVFREQ_GOV_SUSPEND, NULL);
  

+} +EXPORT_SYMBOL(devfreq_suspend_device);

+/**

• • devfreq_resume_device() - Resume devfreq of a device.
• • @devfreq the devfreq instance to be resumed
• */

+int devfreq_resume_device(struct devfreq *devfreq) +{

• if (!devfreq)
  

•         return -EINVAL;
  

• return devfreq->governor->event_handler(devfreq,
  

•                         DEVFREQ_GOV_RESUME, NULL);
  

+} +EXPORT_SYMBOL(devfreq_resume_device);

static ssize_t show_governor(struct device *dev, struct device_attribute *attr, char *buf) { diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h index bb3aff3..26432ac 100644 --- a/drivers/devfreq/governor.h +++ b/drivers/devfreq/governor.h @@ -22,6 +22,8 @@ #define DEVFREQ_GOV_START 0x1 #define DEVFREQ_GOV_STOP 0x2 #define DEVFREQ_GOV_INTERVAL 0x3 +#define DEVFREQ_GOV_SUSPEND 0x4 +#define DEVFREQ_GOV_RESUME 0x5

/* Caution: devfreq->lock must be locked before calling update_devfreq */ extern int update_devfreq(struct devfreq *devfreq); diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c index cf94218..a8ba78c 100644 --- a/drivers/devfreq/governor_simpleondemand.c +++ b/drivers/devfreq/governor_simpleondemand.c @@ -104,6 +104,15 @@ int devfreq_simple_ondemand_handler(struct devfreq *devfreq, case DEVFREQ_GOV_INTERVAL: devfreq_interval_update(devfreq, (unsigned int *)data); break;

• case DEVFREQ_GOV_SUSPEND:
  

•         devfreq_monitor_suspend(devfreq);
  

•         break;
  

• case DEVFREQ_GOV_RESUME:
  

•         devfreq_monitor_resume(devfreq);
  

•         break;
  

• default:
          break;
  }
  

diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index 9cdffde..ee243a3 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -158,6 +158,8 @@ extern struct devfreq *devfreq_add_device(struct device *dev, const struct devfreq_governor *governor, void *data); extern int devfreq_remove_device(struct devfreq *devfreq); +extern int devfreq_suspend_device(struct devfreq *devfreq); +extern int devfreq_resume_device(struct devfreq *devfreq);

/* Helper functions for devfreq user device driver with OPP. */ extern struct opp *devfreq_recommended_opp(struct device *dev, @@ -211,6 +213,16 @@ static int devfreq_remove_device(struct devfreq *devfreq) return 0; }

+static int devfreq_suspend_device(struct devfreq *devfreq) +{

• return 0;
  

+}

+static int devfreq_resume_device(struct devfreq *devfreq) +{

• return 0;
  

+}

static struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq, u32 flags) {

-- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.

-- Regards, Rajagopal