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| author |  Rajmohan Mani <rajmohan.mani@intel.com>
| 2021-04-01 18:42:38 +0300 |
|---|---|---|
| committer |  Mika Westerberg <mika.westerberg@linux.intel.com>
| 2021-06-01 10:53:31 +0300 |
| commit | 3fb10ea4ce86d4d06622be894099c59872e92c57 (patch) | |
| tree | 9fbeb49811791a1a415272603300868a78a65102 /Documentation/admin-guide | |
| parent | thunderbolt: Add additional USB4 port operations for retimer access (diff) | |
| download | linux-3fb10ea4ce86d4d06622be894099c59872e92c57.tar.gz linux-3fb10ea4ce86d4d06622be894099c59872e92c57.tar.bz2 linux-3fb10ea4ce86d4d06622be894099c59872e92c57.zip | |
thunderbolt: Add support for retimer NVM upgrade when there is no link
With help from platform firmware (ACPI) it is possible to power on
retimers even when there is no USB4 link (e.g nothing is connected to
the USB4 ports). This allows us to bring the USB4 sideband up so that we
can access retimers and upgrade their NVM firmware.
If the platform has support for this, we expose two additional
attributes under USB4 ports: offline and rescan. These can be used to
bring the port offline, rescan for the retimers and put the port online
again. The retimer NVM upgrade itself works the same way than with cable
connected.
Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/thunderbolt.rst | 29 |
1 files changed, 29 insertions, 0 deletions
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 |