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diff --git a/Documentation/hwmon/drivetemp.rst b/Documentation/hwmon/drivetemp.rst new file mode 100644 index 000000000..0b1cf2f91 --- /dev/null +++ b/Documentation/hwmon/drivetemp.rst @@ -0,0 +1,70 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Kernel driver drivetemp +======================= + + +References +---------- + +ANS T13/1699-D +Information technology - AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS) + +ANS Project T10/BSR INCITS 513 +Information technology - SCSI Primary Commands - 4 (SPC-4) + +ANS Project INCITS 557 +Information technology - SCSI / ATA Translation - 5 (SAT-5) + + +Description +----------- + +This driver supports reporting the temperature of disk and solid state +drives with temperature sensors. + +If supported, it uses the ATA SCT Command Transport feature to read +the current drive temperature and, if available, temperature limits +as well as historic minimum and maximum temperatures. If SCT Command +Transport is not supported, the driver uses SMART attributes to read +the drive temperature. + + +Usage Note +---------- + +Reading the drive temperature may reset the spin down timer on some drives. +This has been observed with WD120EFAX drives, but may be seen with other +drives as well. The same behavior is observed if the 'hdtemp' or 'smartd' +tools are used to access the drive. +With the WD120EFAX drive, reading the drive temperature using the drivetemp +driver is still possible _after_ it transitioned to standby mode, and +reading the drive temperature in this mode will not cause the drive to +change its mode (meaning the drive will not spin up). It is unknown if other +drives experience similar behavior. + +A known workaround for WD120EFAX drives is to read the drive temperature at +intervals larger than twice the spin-down time. Otherwise affected drives +will never spin down. + + +Sysfs entries +------------- + +Only the temp1_input attribute is always available. Other attributes are +available only if reported by the drive. All temperatures are reported in +milli-degrees Celsius. + +======================= ===================================================== +temp1_input Current drive temperature +temp1_lcrit Minimum temperature limit. Operating the device below + this temperature may cause physical damage to the + device. +temp1_min Minimum recommended continuous operating limit +temp1_max Maximum recommended continuous operating temperature +temp1_crit Maximum temperature limit. Operating the device above + this temperature may cause physical damage to the + device. +temp1_lowest Minimum temperature seen this power cycle +temp1_highest Maximum temperature seen this power cycle +======================= ===================================================== |