On Thursday, September 27, 2012, Aaron Lu wrote:
> On 09/27/2012 10:42 PM, Alan Stern wrote:
> > On Thu, 27 Sep 2012, Aaron Lu wrote:
> >
> >>> Moreover, I'd like to migrate SCSI drivers to the PM handling based on
> >>> struct
> >>> dev_pm_ops eventually and your change is kind of going in the opposite
> >>> direction. I don't know how much effort the migration is going to take,
> >>> though, so perhaps we can just make this change first.
> >>
> >> Does the following change look OK?
> >>
> >> diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c
> >> index dc0ad85..1fb7ccc 100644
> >> --- a/drivers/scsi/scsi_pm.c
> >> +++ b/drivers/scsi/scsi_pm.c
> >> @@ -143,7 +143,15 @@ static int scsi_runtime_suspend(struct device *dev)
> >>
> >> dev_dbg(dev, "scsi_runtime_suspend\n");
> >> if (scsi_is_sdev_device(dev)) {
> >> - err = scsi_dev_type_suspend(dev, PMSG_AUTO_SUSPEND);
> >> + err = scsi_device_quiesce(to_scsi_device(dev));
> >> + if (err)
> >> + goto out;
> >> +
> >> + err = pm_generic_runtime_suspend(dev);
> >> + if (!err)
> >> + goto out;
> >> +
> >> + scsi_device_resume(to_scsi_device(dev));
> >> if (err == -EAGAIN)
> >> pm_schedule_suspend(dev, jiffies_to_msecs(
> >> round_jiffies_up_relative(HZ/10)));
> >
> > Maybe in the end it will be better, but for now this looks like
> > unnecessary code duplication. Basically you are copying
> > scsi_dev_type_suspend() into scsi_runtime_suspend(), except that you
> > omitted the debugging statement.
>
> And I've used pm_generic_runtime_suspend :-)
> That would allow me to write runtime callbacks of dev_pm_ops for
> indivisual scsi drivers, like sr.
Well, actually, I meant something different.
The above patch would make it possible for drivers to provide runtime PM
callbacks through dev->driver.pm, but drv->suspend and drv->resume would
still be used for system suspend/resume (and hibernation).
The transition to struct dev_pm_ops I meant, however, would be to start using
callbacks from dev->driver.pm for _all_ device PM operations by default and
fall back to drv->suspend and drv->resume for the drivers whose dev->driver.pm
is NULL (along the lines of what PCI does). The next step would be to
convert all drivers to use dev->driver.pm only.
So I wouldn't like any drivers to use dev->driver.pm callbacks for some
operations and drv->suspend and drv->resume for the remaining ones at the
same time.
Thanks,
Rafael
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