On Thu, 6 Sep 2012, Aaron Lu wrote:

quoted

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?

Alan Stern