On Tue, 20 Nov 2007, James Bottomley wrote: > I don't really know ... I don't have a clear idea of what you're trying > to do. I know Alan said it was something simple, but from what you're > saying it sounds like you need a full blown power management > infrastructure in all three places. Basically that's right. The higher-level drivers already have some PM infrastructure; all we would have to add would be idle-timeout detection. The midlayer has to be involved in order to coordinate between the high-level and the low-level drivers. The key addition is to get the low-level drivers involved. The main point I'm aiming for is to have the midlayer to inform the LLD when all the devices on a particular bus are "idle". At that point the LLD is free to suspend or power down the transport. Conversely, if the transport is suspended and an I/O request arrives, the LLD has to be told to reactivate the transport. Without some such form of communication, there's no way to know when the tranport can safely be suspended. Does that clarify things? Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
