On Mon, 16 Jan 2012, Oliver Neukum wrote: > Hi, > > I am working on getting this solved and a couple of questions have arisen: This is not an easy thing to do correctly. For example, consider the fact that suspending a bus-powered rotating disk drive will require sending commands to write the cache and spin down the disk. And don't forget the fact that many card readers signal a media change when they resume. When I was thinking about this sort of thing, I came to the conclusion that the right place to do it would be in the block layer core. SCSI requests all funnel through there. > 1. who is responsible for resuming a device when a command arives? > the storage driver or sd? > If sd the problem is that sd doesn't know when a host can suspend attached disks. Currently, nobody is responsible. That's because no commands arrive unless the device has been opened (except for trivial things like the initial scanning), and opening the device file causes an autoresume. > 2. Do commands need to be marked for relating to PM tasks? Yes, they do. 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
