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path: root/drivers/thunderbolt/tmu.c
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2019-12-18thunderbolt: Add support for Time Management UnitRajmohan Mani
Time Management Unit (TMU) is included in each USB4 router. It is used to synchronize time across the USB4 fabric. By default when USB4 router is plugged to the domain, its TMU is turned off. This differs from Thunderbolt (1, 2 and 3) devices whose TMU is by default configured to bi-directional HiFi mode. Since time synchronization is needed for proper Display Port tunneling this means we need to configure the TMU on USB4 compliant devices. The USB4 spec allows some flexibility on how the TMU can be configured. This makes it possible to enable link power management states (CLx) in certain topologies, where for example DP tunneling is not used. TMU can also be re-configured dynamicaly depending on types of tunnels created over the USB4 fabric. In this patch we simply configure the TMU to be in bi-directional HiFi mode. This way we can tunnel any kind of traffic without need to perform complex steps to re-configure the domain dynamically. We can add more fine-grained TMU configuration later on when we start enabling CLx states. 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> Link: https://lore.kernel.org/r/20191217123345.31850-8-mika.westerberg@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>