On Mon, May 23 2005, James Bottomley wrote: > On Mon, 2005-05-23 at 16:45 -0400, Jeff Garzik wrote: > > On Mon, May 23, 2005 at 03:41:15PM -0500, James Bottomley wrote: > > > The thread petered out before a resolution, however, I think > > > at least disk devices should be doing a synchronize cache on suspend. > > > > Agreed. > > OK, try this as a straw horse. It plumbs our scsi bus model into > suspend and resume via the driver (which would be the ULD) function. > The only ULD which has an extra function is sd, and all it does is > synchronize the cache if it was writeback. I believe you translate SYNC > CACHE in libata, so this patch should be sufficient (unless we still > have a problem with ATA devices that lie about their cache types?) > > I think this is sufficient, because if the LLD also wants this > information, it can get it from the model of the bus it's attached to. suspend/resume is a lot more complicated than just flushing a cache, the below will probably get you safe asleep but you will never get devices alive again after power-up on suspend-to-ram. I also greatly prefer issuing a standby command to the drive after the flush, so that we don't risk using the emergency parks of the drive. If a drive happens to lie about wrt the flush command, it gets an extra chance to flush the cache as it now knows that power will be gone very soon. So I think the ->suspend/->resume hooks should belong to the LLD, not the ULD as the ULD has no idea how to suspend all devices types. -- Jens Axboe - : 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
