Am Samstag, 1. August 2009 00:01:27 schrieb Sarah Sharp: > Hi Oliver, Hello, > I know you worked on several versions of a mass storage device > autosuspend patch. Alan wrote them, Pavel and I tried to finish them. > ISTR that they got dropped because the USB core > turned on autosuspend by default and some USB MSDs with spinning disks > didn't park their heads when they were told to suspend. Were there > any other problems with the patches? Yes, they basically come down to enclosures cutting power to the devices. This means - the cache in the drive is lost - any setting local to the drive might be lost > I'm wondering if now that userspace has to enable autosuspend if we can > get away with re-adding those patches. This is basically a judgement call. How much damage is acceptable if autosuspend is activated on a device that can't handle it? We felt that filesystem corruption is beyond the pale in any case. The data loss issue can be solved, but it can't be easily solved cleanly. An implementation to do it the dirty way existed. Alan and I differed on accepatibility. But I never managed to find a solution to vendor specific commands over sd. The possibility to run generic commands over sd is a nightmare from a pm viewpoint. I was forced to disable autosuspend in literally more than a dozen points and sometimes permanently. And it took heavy surgery to the SCSI layer. It was hopeless. It seems to me that the design would need to be discussed and we need to find a consensus on how far we are willing to let autosuspend degrade functionality. 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
