Am Donnerstag, 12. Januar 2012, 16:22:08 schrieb Alan Stern: > On Wed, 11 Jan 2012, Sarah Sharp wrote: > > > > (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.) > > > > Oh, so a USB CD drive won't get auto-suspended at all? > > That's right. The only high-level SCSI driver that supports > autosuspend is sd, so SCSI tape drives won't get autosuspended either. Now that you mention it, I am wondering about sd. 1. sd_open() calls scsi_autopm_get_device(sdev) but only in the error case it calls scsi_autopm_put_device(sdev). So any mount or open should prevent the device from autosuspending. The behavior is certainly correct, but it seems to be in conflict with your statement that it suspends after each command. 2. scsi_autopm_get_device(sdev) is called unconditionally on each open. But according to the comment on the top of sd_release(). scsi_autopm_put_device(sdev) would be called only for the last close. Doesn't that mean that concurrent open calls for a disk disable autosuspend permanently? Regards Oliver -- 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
