On Thursday 06 September 2012 13:08:18 Alan Stern wrote:
> On Thu, 6 Sep 2012, Oliver Neukum wrote:
>
> > On Thursday 06 September 2012 11:06:49 Alan Stern wrote:
> > > On Thu, 6 Sep 2012, Aaron Lu wrote:
> > >
> > > > > That's why we have an autosuspend delay. Although for some reason
> > > > > the
> > > > > SCSI subsystem doesn't use it currently... We need to add a call to
> > > > > pm_runtime_use_autosuspend() in scsi_sysfs_add_sdev(). Likewise, the
> > > > > pm_schedule_suspend() call in scsi_runtime_idle() should be changed
> > > > > to
> > > > > pm_runtime_autosuspend(). And there should be calls to
> > > > > pm_runtime_set_autosuspend_delay() in the sd and sr drivers.
> > > >
> > > > I tried to use autosuspend when preparing the patch, but the fact that
> > > > the devices will be polled every 2 seconds make it impossible to enter
> > > > suspend state if the autosuspend delay is larger than that.
> > >
> > > You can always increase the polling interval.
> > >
> > > But in the long run that wouldn't be a good solution. What I'd really
> > > like is a way to do the status polling without having it reset the
> > > idle timer.
> > >
> > > Oliver, what do you think? Would that be a good solution?
> >
> > Well, we could introduce a flag into the requests for the polls.
> > But best would be to simply declare a device immediately idle
> > as soon as we learn that it has no medium. No special casing
> > would be needed.
>
> We could do that, but what about idle drives that do have media?
Then we do have a problem. To handle this optimally we'd have to make
a difference between the first time a new medium is noticed and later
polls.
Regards
Oliver
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