On 05/24/05 02:53, Jeff Garzik wrote: > You are right about issuing the standby command after flush. I don't > think an LLD hook is the proper way to accomplish it, however. > > The SCSI layer needs to issue the START STOP UNIT command in response to > a suspend event, and libata-scsi will (per SAT spec) translate that into > the ATA standby command. Merely following the relevant SCSI+SAT+ATA > standards gets us there. An SSU command may not be viable as the device may be shared on the domain (i.e. accessed by another initiator). > Longer term, SATA PM through SCSI will have three facets: > > * Device PM. This is best handled by the device class driver (sd/sr/st). In terms of cache syncronization yes. But we may not be the only initiator. > * Bus PM. This is best handled by the transport class driver (need to > write for SATA and SAS). This is tricky. Kudos to Doug's answer. One thing to remember is that this is intricately entangled with host PM. That is, if a device is unplugged from the domain -- would one want to computer to come out of its current power saving mode? Probably not. > * Host PM. This is handled in the obvious manner, using existing PM > driver hooks. PCI D0/D3, etc. Then D3->D0 would be equivalent to reinintialization of the PCI device, doing domain discovery as usual, etc. > I can describe how this will look when libata is divorced from SCSI, if > you would like, too... Please Jeff. A concern is SATA devices behind SAS HAs (host adapters). A straightforward translation provided by libata would be a goal. Luben - : 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
