Re: [PATCHSET] hotplug polling, take 5

[Tejun Heo <htejun@gmail.com>]

Jeff Garzik wrote:
> Tejun Heo wrote:
>> Hello, all.
>>
>> This is the fifth take of hotplug polling patchset.  This take doesn't
>> contain any real change than rebasing over the current upstream[U].
>> PMP patchset will be posted soon on top of this patchset and I wanted
>> to avoid confusion by posting patchsets in order.
>>
>> As the name implies, this patchset implements hotplug by polling.
>> hp-poll is used to
>>
>> * Monitor ports EH gave up.  When EH gives up on a port, it freezes
>>   the port to protect the rest of the system from it.  The user used
>>   to have to issue manual scan to retry the port.  hp-poll can monitor
>>   such port and retry it when hotplug event is detected.  This is also
>>   used by PMP support.
>>
>> * Support hotplug on controllers which can report hotplug conditions
>>   but cannot raise interrupt.
> 
> Patchset seems sane.  I'll need to re-read patch #1 in depth, but I give 
> everything a tentative ACK for now.
> 
> My biggest concern is power usage.  On laptops for example, the 99% 
> common case is that the user will never hot[un]plug a drive, so we 
> shouldn't waste power bothering with poking disabled ports.

Link powersave patchset should handle that together but I'm still not 
sure what to do w/ user interface (which sysfs node to use).  Also, 
controllers which are used on laptops && use hp-poll by default are 
sata_nv (old ones) and some variant of sata_sil used in ati chipset. 
So, it shouldn't cause trouble for most laptop users.

-- 
tejun