libata: update documentation for sysfs interfaces (0a65e125) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-block-device

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		What: /sys/block/*/device/sw_activity
		Date: Jun, 2008
		KernelVersion: v2.6.27
		Contact: linux-ide@vger.kernel.org
		Description:
		(RW) Used by drivers which support software controlled activity
		LEDs.

		It has the following valid values:

		0 OFF - the LED is not activated on activity
		1 BLINK_ON - the LED blinks on every 10ms when activity is
		detected.
		2 BLINK_OFF - the LED is on when idle, and blinks off
		every 10ms when activity is detected.

		Note that the user must turn sw_activity OFF it they wish to
		control the activity LED via the em_message file.


		What: /sys/block/*/device/unload_heads
		Date: Sep, 2008
		KernelVersion: v2.6.28
		Contact: linux-ide@vger.kernel.org
		Description:
		(RW) Hard disk shock protection

		Writing an integer value to this file will take the heads of the
		respective drive off the platter and block all I/O operations
		for the specified number of milliseconds.

		- If the device does not support the unload heads feature,
		access is denied with -EOPNOTSUPP.
		- The maximal value accepted for a timeout is 30000
		milliseconds.
		- A previously set timeout can be cancelled and disk can resume
		normal operation immediately by specifying a timeout of 0.
		- Some hard drives only comply with an earlier version of the
		ATA standard, but support the unload feature nonetheless.
		There is no safe way Linux can detect these devices, so this
		is not enabled by default. If it is known that your device
		does support the unload feature, then you can tell the kernel
		to enable it by writing -1. It can be disabled again by
		writing -2.
		- Values below -2 are rejected with -EINVAL

		For more information, see
		Documentation/laptops/disk-shock-protection.txt


		What: /sys/block/*/device/ncq_prio_enable
		Date: Oct, 2016
		KernelVersion: v4.10
		Contact: linux-ide@vger.kernel.org
		Description:
		(RW) Write to the file to turn on or off the SATA ncq (native
		command queueing) support. By default this feature is turned
		off.

Documentation/ABI/testing/sysfs-class-scsi_host

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		@@ -27,3 +27,92 @@ Description: This file contains the current status of the "SSD Smart Path"
		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.

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