On Tue, 2012-09-18 at 15:00 +0800, Aaron Lu wrote:
> When scsi device received stop command, it will take care of its
> internal cache before enters stopped power condition. This command is
> translated to standby immediate in libata-scsi, but standby doesn't
> imply flush cache for ATA device, so to issue stop command to ATA
> device, an additional flush cache has to be issued.
>
> Introduce this flag so that when we are to stop the ATA disk in scsi
> disk driver, also flush its internal cache.
>
> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
> ---
> include/scsi/scsi_device.h | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
> index 4712aa1..26c3621 100644
> --- a/include/scsi/scsi_device.h
> +++ b/include/scsi/scsi_device.h
> @@ -160,6 +160,7 @@ struct scsi_device {
> unsigned ready_to_power_off:1; /* Device is ready to be powered off */
> unsigned powered_off:1; /* Device is powered off */
> unsigned may_power_off:1; /* Power off is allowed by user */
> + unsigned sync_before_stop:1; /* Sync cache before stop */
Why do you need this?
Surely it's all conditioned on the WCE flag. If WCE isn't set, the
cache is write through (or uncached) and there's no need for a sync
before power down.
James
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