On Thu, 2012-09-13 at 17:07 +0800, Aaron Lu wrote: > On 09/13/2012 04:56 PM, James Bottomley wrote: > > So what's the target audience for the feature. If it isn't laptops or > > standard desktops, is it the enterprise? > > To make this feature useful for normal laptop user, a better mechanism > for scsi disk runtime pm is needed. Alan Stern and Lin Ming has been > working on this, and I'll see if I can make that patch work later. > > So I think this is basically 2 things, one is the runtime suspend of the > disk, another is when it is runtime suspended, how to remove its power. > I'm currently doing the latter one, which is simpler, so I want to do it > first :-)
Well, I don't like the way the interaction of the patches is going. You're the one proposing powering down the device outside of the standards defined transitions, so you need to be responsible for the actions that necessitates, including synchronizing the cache. The specs (SPC-4) say that cache management is explicitly unnecessary for the standard SCSI power states (Active, Idle, Standby and Stopped), so someone at some point is going to read that and remove the unnecessary cache sync in the code. When that happens, you'll start getting data loss. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
