On Wed, 13 Aug 2008, Oliver Neukum wrote: > > In Alan's patch, SCSI calls scsi_host_template methods (if the LLD > > provides ones) to suspend and resume a Scsi_Host. The LLD can use them > > to work with the underlying infrastructure to determine what can be done > > at that time. I.e. are there other protocols or other initiator-like > > nodes sharing the link? If yes or if "maybe yes", the infrastructure > > keeps the link up. If not, it can move it into a low-power state. > > That is a parculiar way of viewing it. Alan's patch introduce runtime > pm attributes to the devices. Quoting: > > > +/** > + * scsi_suspend_sdev - suspend a SCSI device > + * @sdev: the scsi_device to suspend > + * @msg: Power Management message describing this state transition > + * > + * SCSI devices can't actually be suspended in a literal sense, > + * because SCSI doesn't have any notion of power management. Instead > + * this routine drains the request queue and calls the ULD's suspend > + * method to flush caches, spin-down drives, and so on. > + * > + * If the suspend succeeds, we call scsi_autosuspend_host to decrement > + * the host's count of unsuspended devices and invoke the LLD's suspend > + * method. > > So you cannot operate on the link independent from the devices. With the original patch, you can't operate on the link independent from the devices. But with the revised patch (whenever I manage to find time to write it!), you _will_ be able to. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
