On Fri, Feb 17, 2012 at 11:07 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 17 Feb 2012, Zhang, Rui wrote: > >> > Do you basically want >> > the ZPODD always to be suspended and resumed along with the ATA port, >> >> No. ZPODD suspends itself, which put ZPODD to a SCSI low power state (NOT power off/D3_COLD). >> And then it is the "Runtime PM core" that suspends ATA port after ZPODD being suspended. >> And the .runtime_suspend callback for ATA port actually turns off the ZPODD power. >> >> During resume, ATA port is resumed first because of the ACPI wakeup event. >> But in fact, this wakeup event should be read as "ZPODD remote wakeup signal", thus runtime resume request is sent to ZPODD, done by Patch 3/6. >> >> > or should it be possible to suspend the ZPODD while the port remains >> > running? >> > >> Sure, but the power is still on at this time. > > Then maybe you can use pm_runtime_no_callbacks() for the ZPODD device. > It's explained in Documentation/power/runtime_pm.txt, and I use it for > USB interfaces. If pm_runtime_no_callbacks() is used, runtime PM sysfs attributes won't be created. Then how to disable ZPODD feature in userspace? Currently, I use "control" file of scsi device to enable/disable ZPODD, for example echo auto > /sys/devices/pci0000:00/0000:00:1f.2/ata0/host1/target1:0:0/1:0:0:0/power/control echo on > /sys/devices/pci0000:00/0000:00:1f.2/ata0/host1/target1:0:0/1:0:0:0/power/control > > The idea is that the ZPODD will never receive any runtime PM callbacks > from the PM core. Instead the ATA port callback routines will be > responsible for power management of the ZPODD device. Does the ATA port callback also responsible to resume its child? For example, /sys/devices/pci0000:00/0000:00:1f.2/ata0/host1/target1:0:0/1:0:0:0/ ata0 is resumed. Then who will be responsible to resume host1, target1:0:0 and 1:0:0:0? Or do you mean that we don't need to resume these devices at all? host1 and target1:0:0 are logical devices, but I think 1:0:0:0 is not. Thanks, Lin Ming -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
