[SCSI] hpsa: allow user to disable accelerated i/o path
Allow SSD Smart Path for a controller to be disabled by
the user, regardless of settings in controller firmware
or array configuration.
To disable: echo 0 > /sys/class/scsi_host/host<id>/acciopath_status
To re-enable: echo 1 > /sys/class/scsi_host/host<id>/acciopath_status
To check state: cat /sys/class/scsi_host/host<id>/acciopath_status
Signed-off-by: Scott Teel <scott.teel@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/Documentation/ABI/testing/sysfs-class-scsi_host b/Documentation/ABI/testing/sysfs-class-scsi_host
index 29a4f89..0eb255e 100644
--- a/Documentation/ABI/testing/sysfs-class-scsi_host
+++ b/Documentation/ABI/testing/sysfs-class-scsi_host
@@ -11,3 +11,19 @@
guaranteed. The 'isci_id' attribute unambiguously identifies
the controller index: '0' for the first controller,
'1' for the second.
+
+What: /sys/class/scsi_host/hostX/acciopath_status
+Date: November 2013
+Contact: Stephen M. Cameron <scameron@beardog.cce.hp.com>
+Description: This file contains the current status of the "SSD Smart Path"
+ feature of HP Smart Array RAID controllers using the hpsa
+ driver. SSD Smart Path, when enabled permits the driver to
+ send i/o requests directly to physical devices that are part
+ of a logical drive, bypassing the controllers firmware RAID
+ stack for a performance advantage when possible. A value of
+ '1' indicates the feature is enabled, and the controller may
+ use the direct i/o path to physical devices. A value of zero
+ means the feature is disabled and the controller may not use
+ the direct i/o path to physical devices. This setting is
+ controller wide, affecting all configured logical drives on the
+ controller. This file is readable and writable.
