On Tue, 2007-03-20 at 13:58 -0400, Douglas Gilbert wrote: > I note at this point that the IMMED bit in the > START STOP UNIT cdb is clear. [The code might > note that as well.] All SCSI disks that I have > seen, implement the IMMED bit and according to > the SAT standard, so should SAT layers like the > one in libata. > > With the IMMED bit clear: > - on spin up, it will wait until disk is ready. > Okay unless there are a lot of disks, in > which case we could ask Matthew Wilcox for help > - on spin down, will wait until media is > stopped. That could be 20 seconds, and if there > were multiple disks .... > > I guess the question is do we need to wait until a > disk is spun down before dropping power to it > and suspending. Realistically, if you're thinking of doing a bank spin up / spin down with IMMED=1 I suspect we can wait and see if anyone has sufficient need for it to be implemented before trying. The majority of the suspend/resume cases are laptops with a single disc ... and there immed is irrelevant to them. I think we need assurance that the head is parked before full suspend, yes, so IMMED=0 seems the easiest way to do this. James - 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
