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Commit b1c7fe26 authored by Aishwarya Pant's avatar Aishwarya Pant Committed by Tejun Heo
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libata: transport: cleanup documentation of sysfs interface 



Clean-up the documentation of sysfs interfaces to be in the same format
as described in Documentation/ABI/README. This will be useful for
tracking changes in the ABI. Attributes are grouped by function (device,
link or port) and then by date added.

This patch also adds documentation for one attribute -
/sys/class/ata_port/ataX/port_no

Signed-off-by: default avatarAishwarya Pant <aishpant@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent da77d76b

Documentation/ABI/testing/sysfs-ata

+100 −71
Original line number Diff line number Diff line 
What:		/sys/class/ata_...

Date:		August 2008

Contact:	Gwendal Grignou<gwendal@google.com>

Description:



Provide a place in sysfs for storing the ATA topology of the system.  This allows

retrieving various information about ATA objects.

		Provide a place in sysfs for storing the ATA topology of the

		system. This allows retrieving various information about ATA

		objects.



Files under /sys/class/ata_port

-------------------------------



	For each port, a directory ataX is created where X is the ata_port_id of

	the port. The device parent is the ata host device.

For each port, a directory ataX is created where X is the ata_port_id of the

port. The device parent is the ata host device.





idle_irq (read)

What:		/sys/class/ata_port/ataX/nr_pmp_links

What:		/sys/class/ata_port/ataX/idle_irq

Date:		May, 2010

KernelVersion:	v2.6.37

Contact:	Gwendal Grignou <gwendal@chromium.org>

Description:

		nr_pmp_links:	(RO) If a SATA Port Multiplier (PM) is

				connected, the number of links behind it.



	Number of IRQ received by the port while idle [some ata HBA only].

		idle_irq:	(RO) Number of IRQ received by the port while

				idle [some ata HBA only].



nr_pmp_links (read)



	If a SATA Port Multiplier (PM) is connected, number of link behind it.

What:		/sys/class/ata_port/ataX/port_no

Date:		May, 2013

KernelVersion:	v3.11

Contact:	Gwendal Grignou <gwendal@chromium.org>

Description:

		(RO) Host local port number. While registering host controller,

		port numbers are tracked based upon number of ports available on

		the controller. This attribute is needed by udev for composing

		persistent links in /dev/disk/by-path.



Files under /sys/class/ata_link

-------------------------------



	Behind each port, there is a ata_link. If there is a SATA PM in the

	topology, 15 ata_link objects are created.

Behind each port, there is a ata_link. If there is a SATA PM in the topology, 15

ata_link objects are created.



	If a link is behind a port, the directory name is linkX, where X is

	ata_port_id of the port.

	If a link is behind a PM, its name is linkX.Y where X is ata_port_id

	of the parent port and Y the PM port.

If a link is behind a port, the directory name is linkX, where X is ata_port_id

of the port. If a link is behind a PM, its name is linkX.Y where X is

ata_port_id of the parent port and Y the PM port.



hw_sata_spd_limit



	Maximum speed supported by the connected SATA device.



sata_spd_limit

What:		/sys/class/ata_link/linkX[.Y]/hw_sata_spd_limit

What:		/sys/class/ata_link/linkX[.Y]/sata_spd_limit

What:		/sys/class/ata_link/linkX[.Y]/sata_spd

Date:		May, 2010

KernelVersion:	v2.6.37

Contact:	Gwendal Grignou <gwendal@chromium.org>

Description:

		hw_sata_spd_limit:	(RO) Maximum speed supported by the

					connected SATA device.



	Maximum speed imposed by libata.

		sata_spd_limit:		(RO) Maximum speed imposed by libata.



sata_spd

		sata_spd:		(RO) Current speed of the link

					eg. 1.5, 3 Gbps etc.



	Current speed of the link [1.5, 3Gps,...].



Files under /sys/class/ata_device

---------------------------------



	Behind each link, up to two ata device are created.

Behind each link, up to two ata devices are created.

The name of the directory is devX[.Y].Z where:

- X is ata_port_id of the port where the device is connected,

- Y the port of the PM if any, and

	- Z the device id: for PATA, there is usually 2 devices [0,1],

	only 1 for SATA.



class

	Device class. Can be "ata" for disk, "atapi" for packet device,

	"pmp" for PM, or "none" if no device was found behind the link.



dma_mode



	Transfer modes supported by the device when in DMA mode.

	Mostly used by PATA device.



pio_mode



	Transfer modes supported by the device when in PIO mode.

	Mostly used by PATA device.



xfer_mode



	Current transfer mode.



id



	Cached result of IDENTIFY command, as described in ATA8 7.16 and 7.17.

	Only valid if the device is not a PM.

- Z the device id: for PATA, there is usually 2 devices [0,1], only 1 for SATA.





What:		/sys/class/ata_device/devX[.Y].Z/spdn_cnt

What:		/sys/class/ata_device/devX[.Y].Z/gscr

What:		/sys/class/ata_device/devX[.Y].Z/ering

What:		/sys/class/ata_device/devX[.Y].Z/id

What:		/sys/class/ata_device/devX[.Y].Z/pio_mode

What:		/sys/class/ata_device/devX[.Y].Z/xfer_mode

What:		/sys/class/ata_device/devX[.Y].Z/dma_mode

What:		/sys/class/ata_device/devX[.Y].Z/class

Date:		May, 2010

KernelVersion:	v2.6.37

Contact:	Gwendal Grignou <gwendal@chromium.org>

Description:

		spdn_cnt:	(RO) Number of times libata decided to lower the

				speed of link due to errors.



gscr

		gscr:		(RO) Cached result of the dump of PM GSCR

				register. Valid registers are:



	Cached result of the dump of PM GSCR register.

	Valid registers are:

				0:      SATA_PMP_GSCR_PROD_ID,

				1:	SATA_PMP_GSCR_REV,

				2:      SATA_PMP_GSCR_PORT_INFO,
@@ -88,23 +97,43 @@ gscr 
				64:     SATA_PMP_GSCR_FEAT,

				96:     SATA_PMP_GSCR_FEAT_EN,

				130:    SATA_PMP_GSCR_SII_GPIO



				Only valid if the device is a PM.



trim

		ering:		(RO) Formatted output of the error ring of the

				device.



		id:		(RO) Cached result of IDENTIFY command, as

				described in ATA8 7.16 and 7.17. Only valid if

				the device is not a PM.



		pio_mode:	(RO) Transfer modes supported by the device when

				in PIO mode. Mostly used by PATA device.



		xfer_mode:	(RO) Current transfer mode



	Shows the DSM TRIM mode currently used by the device. Valid

		dma_mode:	(RO) Transfer modes supported by the device when

				in DMA mode. Mostly used by PATA device.



		class:		(RO) Device class. Can be "ata" for disk,

				"atapi" for packet device, "pmp" for PM, or

				"none" if no device was found behind the link.





What:		/sys/class/ata_device/devX[.Y].Z/trim

Date:		May, 2015

KernelVersion:	v4.10

Contact:	Gwendal Grignou <gwendal@chromium.org>

Description:

		(RO) Shows the DSM TRIM mode currently used by the device. Valid

		values are:

	unsupported:		Drive does not support DSM TRIM

	unqueued:		Drive supports unqueued DSM TRIM only

	queued:			Drive supports queued DSM TRIM

	forced_unqueued:	Drive's queued DSM support is known to be

				buggy and only unqueued TRIM commands

				are sent



spdn_cnt

		unsupported:		Drive does not support DSM TRIM



	Number of time libata decided to lower the speed of link due to errors.

		unqueued:               Drive supports unqueued DSM TRIM only



ering

		queued:                 Drive supports queued DSM TRIM



	Formatted output of the error ring of the device.
 
		forced_unqueued:	Drive's queued DSM support is known to

					be buggy and only unqueued TRIM commands

					are sent