On Fri, 2010-10-22 at 02:34 +0800, Alan Stern wrote:
> On Fri, 15 Oct 2010, Alan Cox wrote:
>
> > From: Hong Liu <hong.liu@xxxxxxxxx>
> >
> >
> > Update the driver for the needed runtime power features. Remove the old
> > user controlled power functions.
> >
> > Signed-off-by: Hong Liu <hong.liu@xxxxxxxxx>
> > Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
>
> > diff --git a/drivers/misc/apds9802als.c b/drivers/misc/apds9802als.c
> > index fbe4960..15f9436 100644
> > --- a/drivers/misc/apds9802als.c
> > +++ b/drivers/misc/apds9802als.c
>
> > @@ -265,13 +274,34 @@ static int apds9802als_suspend(struct i2c_client *client, pm_message_t mesg)
> >
> > static int apds9802als_resume(struct i2c_client *client)
> > {
> > - struct als_data *data = i2c_get_clientdata(client);
> > + als_set_default_config(client);
> > +
> > + pm_runtime_get(&client->dev);
> > + pm_runtime_put(&client->dev);
> > + return 0;
> > +}
>
Hi, Alan
Thanks for your review.
> This almost certainly does not do what you think.
>
> pm_runtime_get() will increment the device's usage count and queue an
> asynchronous resume request. However, since the PM workqueue is frozen
> during system sleep transitions, the device will remain suspended.
>
> The pm_runtime_put() will decrement the usage count again, but since
> there is already an async resume on the queue it will not queue an
> async suspend. The final result will be that when tasks are unfrozen,
> the device will finally be resumed -- long after it should have been.
>
> It looks like what you want to do here is simply call
> apds9802als_runtime_resume() directly.
You mean apds9802als_runtime_suspend()? I want to put the device into
runtime suspended state, can I just call pm_runtime_suspend() directly?
> And according to the advice in
> Documentation/power/runtime_pm.txt section 6, you should also call
>
> pm_runtime_disable(dev);
> pm_runtime_set_active(dev);
> pm_runtime_enable(dev);
>
> You probably also do not want the asynchronous calls to
> pm_runtime_get() and pm_runtime_put() in apds9802als_probe(). A more
> common sequence is:
>
> pm_runtime_set_active(dev);
> pm_runtime_enable(dev);
I want to put the device into runtime suspend state after probe, so
pm_runtime_suspend() after these two calls is OK?
Thanks,
Hong
>
> Alan Stern
>
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