On Sun, 11 Jul 2010, Oliver Neukum wrote: > Am Samstag, 10. Juli 2010, 20:10:19 schrieb Alan Stern: > > > This patch works fine with empty SD card readers. Some thumb drives > > > will also autosuspend when they are unmounted or ejected from the Gnome > > > filesystem GUI. Other thumb drives always report "Medium may have > > > changed" if they need to flash stupid LEDs, like the original Linux > > > Plumbers Conference thumb drive. > > > > I would prefer not to have this accepted. There already are patches > > waiting in James Bottomley's queue to add runtime PM support to the > > SCSI subsystem; once they are merged, adding autosuspend to usb-storage > > will be a 4-line change -- already written and tested. > > Yes. The original patch was a hack. However this approach has some > merit that could prove important in practice. It seems to me that we'll > have to live with user space polling the devices for new media. > If we cannot prevent it, we need to minimize damage. That requires > > a) detecting the drive is empty > b) suspend immediately without delay > > Sarah has solved the first half of the problem. The SCSI runtime PM patches also solve it, and they do a better job because they will allow autosuspend not only when the drive is empty but also when the device file isn't open. The "without delay" part is solved simply by setting the autosuspend delay to 0. 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
