Elias Oltmanns wrote: > On user request (through sysfs), the IDLE IMMEDIATE command with UNLOAD > FEATURE as specified in ATA-7 is issued to the device and processing of > the request queue is stopped thereafter until the speified timeout > expires or user space asks to resume normal operation. This is supposed > to prevent the heads of a hard drive from accidentally crashing onto the > platter when a heavy shock is anticipated (like a falling laptop > expected to hit the floor). This patch simply stops processing the > request queue. In particular, it does not yet, for instance, defer an > SRST issued in order to recover from an error on the other device on the > interface. For libata, the easiest way to achieve the above would be adding a per-dev EH action, say, ATA_EH_UNLOAD and schedule EH w/ the action OR'd to eh_info->action. The EH_UNLOAD handler can then issue the command wait for the specified number of seconds and continue. This will be pretty simple to implement as command exclusion and stuff are all automatically handled by EH framework. However, SATA or not, there simply isn't a way to abort commands in ATA. Issuing random command while other commands are in progress simply is state machine violation and there will be many interesting results including complete system lockup (ATA controller dying while holding the PCI bus). The only reliable way to abort in-flight commands are by issuing hardreset. However, ATA reset protocol is not designed for quick recovery. The machine is gonna hit the ground hard way before the reset protocol is complete. The only way to solve this nicely is either to build the accelerometer into the drive and let the drive itself protect itself or implement a sideband signal to tell it to duck for cover. For SATA, this sideband signal can be another OOB sequence. If it's ever implemented this way, it will be in SControl, I guess. Well, short of that, all we can do is to wait for the currently in-flight commands to drain and hope that it happens before the machine hits the ground. Also, that the harddrive is not going through one of the longish EH recovery sequences when it starts to fall. :-( -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
