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Diffstat (limited to 'Documentation/admin-guide/thunderbolt.rst')
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diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index f18e881373c4..2ed79f41a411 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -256,6 +256,35 @@ Note names of the NVMem devices ``nvm_activeN`` and ``nvm_non_activeN`` depend on the order they are registered in the NVMem subsystem. N in the name is the identifier added by the NVMem subsystem. +Upgrading on-board retimer NVM when there is no cable connected +--------------------------------------------------------------- +If the platform supports, it may be possible to upgrade the retimer NVM +firmware even when there is nothing connected to the USB4 +ports. When this is the case the ``usb4_portX`` devices have two special +attributes: ``offline`` and ``rescan``. The way to upgrade the firmware +is to first put the USB4 port into offline mode:: + + # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/offline + +This step makes sure the port does not respond to any hotplug events, +and also ensures the retimers are powered on. The next step is to scan +for the retimers:: + + # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/rescan + +This enumerates and adds the on-board retimers. Now retimer NVM can be +upgraded in the same way than with cable connected (see previous +section). However, the retimer is not disconnected as we are offline +mode) so after writing ``1`` to ``nvm_authenticate`` one should wait for +5 or more seconds before running rescan again:: + + # echo 1 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/rescan + +This point if everything went fine, the port can be put back to +functional state again:: + + # echo 0 > /sys/bus/thunderbolt/devices/0-0/usb4_port1/offline + Upgrading NVM when host controller is in safe mode -------------------------------------------------- If the existing NVM is not properly authenticated (or is missing) the |