On Sun, Nov 18, 2012 at 09:07:22PM -0500, Alan Stern wrote:

Hey...

Hey, again. :P

quoted

So, at least for SATA, I think what autopm can do is...

* Trigger zpodd if possible.

* Trigger suspend iff polling isn't happening on the device.

That sums it up nicely.  Of course, the PM core is unaware of details
such as media polling.  What we can do is have the SATA runtime-idle
method return -EBUSY if the device isn't a ZPODD and if polling is
enabled.  Unfortunately I don't think there's any way currently to
trigger autopm when the user turns off polling.  Maybe something could
be added to the appropriate sysfs handler.

Given that genhd event polling and PM are likely to interact with each
other, I think it would be a good idea to implement a proper way for
the two to communicate.  Dunno what it should be tho.  The tricky part
would be mapping the block device to the underlying hardware one.

Thanks.

-- 
tejun