Tejun Heo writes:
 > Mikael Pettersson wrote:
 > > - smartctl -n standby waking Linda's disks from standby is probably
 > >   a disk firmware issue or a smartctl issue. I see no evidence that
 > >   sata_promise is to blame for that.
 > 
 > /me agrees.  I think it's most likely a problem in the firmware.
 > 
 > > - hardreset in sata_promise seems broken. I'll take a closer look
 > >   at that in about a week's time (I'll be busy with other work the
 > >   next couple of days).
 > 
 > This looks like a rather serious problem, so please take a look at
 > this.  Also, after the drive went down, does unplugging and replugging
 > the signal cable fix the problem, if not does doing the same thing
 > with the power cable make any difference?

I couldn't bring the port back up with any combination of signal/power
cable hotplugging. Even rmmod sata_promise; modprobe sata_promise failed
to bring the port back up. Hence my suspicion that hardreset is borked
or doesn't kick in.