On Sat, 22 Sep 2012, Rafael J. Wysocki wrote: > > There are sd devices with removable media. > > OK. Does the SCSI layer distinguish them from devices without removable media? Yes, it does. struct scsi_device has a .removable member, and the Removable flag is part of the response data to the INQUIRY command (which belongs to the primary command set common to all SCSI devices). > > > User space has an interface to disable runtime PM of any device and it looks > > > like that interface should be sufficient to disable the feature in question. > > > Why do you think the new interface is needed? > > > > Because this is not equivalent to doing no runtime PM at all. SCSI > > now defines some powersaving states which do not involve powering > > down and thus losing state. > > I see. So the sr's runtime suspend may be useful even without the power-off > feature, right? Exactly. Even though the drive itself may not be powered off, by putting it into runtime suspend we gain the ability to suspend the ancestor devices. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
