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| author | Mario Limonciello <mario.limonciello@dell.com> | 2017-09-08 18:23:11 +0300 |
|---|---|---|
| committer | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2017-09-20 16:07:22 +0300 |
| commit | ce6a90027c10f970f872de5db0294f9e3e969f1c (patch) | |
| tree | 8f370602c3ae125a6bc68dc3489f395982937069 /Documentation/admin-guide | |
| parent | 2bd6bf03f4c1c59381d62c61d03f6cc3fe71f66e (diff) | |
| download | linux-ce6a90027c10f970f872de5db0294f9e3e969f1c.tar.xz | |
platform/x86: Add driver to force WMI Thunderbolt controller power status
Current implementations of Intel Thunderbolt controllers will go
into a low power mode when not in use.
Many machines containing these controllers also have a GPIO wired up
that can force the controller awake. This is offered via a ACPI-WMI
interface intended to be manipulated by a userspace utility.
This mechanism is provided by Intel to OEMs to include in BIOS.
It uses an industry wide GUID that is populated in a separate _WDG
entry with no binary MOF.
This interface allows software such as fwupd to wake up thunderbolt
controllers to query the firmware version or flash new firmware.
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
[andy fixed merge conflicts and bump kernel version for ABI]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/thunderbolt.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index 6a4cd1f159ca..dadcd66ee12f 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -197,3 +197,18 @@ information is missing. To recover from this mode, one needs to flash a valid NVM image to the host host controller in the same way it is done in the previous chapter. + +Forcing power +------------- +Many OEMs include a method that can be used to force the power of a +thunderbolt controller to an "On" state even if nothing is connected. +If supported by your machine this will be exposed by the WMI bus with +a sysfs attribute called "force_power". + +For example the intel-wmi-thunderbolt driver exposes this attribute in: + /sys/devices/platform/PNP0C14:00/wmi_bus/wmi_bus-PNP0C14:00/86CCFD48-205E-4A77-9C48-2021CBEDE341/force_power + + To force the power to on, write 1 to this attribute file. + To disable force power, write 0 to this attribute file. + +Note: it's currently not possible to query the force power state of a platform. |