On Wed, 11 Jan 2012, Sarah Sharp wrote: > > No; the USB Mass Storage specs say nothing about remote wakeup and > > usb-storage doesn't require it. I haven't heard of any mass-storage > > devices that would send wakeup requests. > > Ok, that's what I thought. Some folks were concerned about bad system > power management they have been seeing, and they were claiming the host > didn't need to poll an empty CD drive if the USB CD drive advertised > remote wakeup in its descriptors. Now I can tell them it's simply not > true. Well, it may be true for all I know. But I haven't run across any USB CD drives like that. And the spec doesn't say anything about it. Besides, what's usb-storage going to do if a CD drive does send a wakeup request? usb-storage doesn't initiate any SCSI commands on its own. All that will happen is the autosuspend timer will expire and the drive will be suspended again. (In addition to all that, the SCSI CD driver currently doesn't support autosuspend. So we can't autosuspend USB CD drives anyway, even if they aren't being polled.) Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
