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Commit 397be946 authored by Rajmohan Mani's avatar Rajmohan Mani Committed by Mario Limonciello
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thunderbolt: Add support for ACPI _DSM to power on/off retimers


Typically retimers can be accessed only when the USB4 link is up (e.g
there is a cable connected). However, sometimes it is useful to be able
to access retimers even if there is nothing connected to the USB4 port.
For instance we may still want to be able to upgrade the retimer NVM
firmware even if the user does not have any USB4 devices. This is
something that USB4 spec leaves to implementers.

In case of ACPI based systems, we can support this by providing a
special _DSM method under each USB4 port. This _DSM can be used to turn
on power to on-board retimers (and cycle it through different modes so
that the sideband becomes usable).

This patch adds support for this _DSM and makes the functionality
available to the rest of the driver through tb_acpi_power_[on|off]_retimers().

Signed-off-by: default avatarRajmohan Mani <rajmohan.mani@intel.com>
Co-developed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Change-Id: I864edfca3a91e0f592fb285422143a67dd253f1a
parent 62333aeb
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