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+What: /sys/class/scsi_host/hostX/isci_id
+Date: June 2011
+Contact: Dave Jiang <dave.jiang@intel.com>
+Description:
+ This file contains the enumerated host ID for the Intel
+ SCU controller. The Intel(R) C600 Series Chipset SATA/SAS
+ Storage Control Unit embeds up to two 4-port controllers in
+ a single PCI device. The controllers are enumerated in order
+ which usually means the lowest number scsi_host corresponds
+ with the first controller, but this association is not
+ 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.
+
+What: /sys/class/scsi_host/hostX/link_power_management_policy
+Date: Oct, 2007
+KernelVersion: v2.6.24
+Contact: linux-ide@vger.kernel.org
+Description:
+ (RW) This parameter allows the user to read and set the link
+ (interface) power management.
+
+ There are four possible options:
+
+ min_power: Tell the controller to try to make the link use the
+ least possible power when possible. This may sacrifice some
+ performance due to increased latency when coming out of lower
+ power states.
+
+ max_performance: Generally, this means no power management.
+ Tell the controller to have performance be a priority over power
+ management.
+
+ medium_power: Tell the controller to enter a lower power state
+ when possible, but do not enter the lowest power state, thus
+ improving latency over min_power setting.
+
+ med_power_with_dipm: Identical to the existing medium_power
+ setting except that it enables dipm (device initiated power
+ management) on top, which makes it match the Windows IRST (Intel
+ Rapid Storage Technology) driver settings. This setting is also
+ close to min_power, except that:
+
+ a) It does not use host-initiated slumber mode, but it does
+ allow device-initiated slumber
+ b) It does not enable low power device sleep mode (DevSlp).
+
+What: /sys/class/scsi_host/hostX/em_message
+What: /sys/class/scsi_host/hostX/em_message_type
+Date: Jun, 2008
+KernelVersion: v2.6.27
+Contact: linux-ide@vger.kernel.org
+Description:
+ em_message: (RW) Enclosure management support. For the LED
+ protocol, writes and reads correspond to the LED message format
+ as defined in the AHCI spec.
+
+ The user must turn sw_activity (under `/sys/block/*/device/`)
+ OFF it they wish to control the activity LED via the em_message
+ file.
+
+ em_message_type: (RO) Displays the current enclosure management
+ protocol that is being used by the driver (for eg. LED, SAF-TE,
+ SES-2, SGPIO etc).
+
+What: /sys/class/scsi_host/hostX/ahci_port_cmd
+What: /sys/class/scsi_host/hostX/ahci_host_caps
+What: /sys/class/scsi_host/hostX/ahci_host_cap2
+Date: Mar, 2010
+KernelVersion: v2.6.35
+Contact: linux-ide@vger.kernel.org
+Description:
+ [to be documented]
+
+What: /sys/class/scsi_host/hostX/ahci_host_version
+Date: Mar, 2010
+KernelVersion: v2.6.35
+Contact: linux-ide@vger.kernel.org
+Description:
+ (RO) Display the version of the AHCI spec implemented by the
+ host.
+
+What: /sys/class/scsi_host/hostX/em_buffer
+Date: Apr, 2010
+KernelVersion: v2.6.35
+Contact: linux-ide@vger.kernel.org
+Description:
+ (RW) Allows access to AHCI EM (enclosure management) buffer
+ directly if the host supports EM.
+
+ For eg. the AHCI driver supports SGPIO EM messages but the
+ SATA/AHCI specs do not define the SGPIO message format of the EM
+ buffer. Different hardware(HW) vendors may have different
+ definitions. With the em_buffer attribute, this issue can be
+ solved by allowing HW vendors to provide userland drivers and
+ tools for their SGPIO initiators.
+
+What: /sys/class/scsi_host/hostX/em_message_supported
+Date: Oct, 2009
+KernelVersion: v2.6.39
+Contact: linux-ide@vger.kernel.org
+Description:
+ (RO) Displays supported enclosure management message types.