Sanjay R Mehta f016326d31 thunderbolt: Fix Thunderbolt 3 display flickering issue on 2nd hot plug onwards
commit 583893a66d upstream.

Previously, on unplug events, the TMU mode was disabled first
followed by the Time Synchronization Handshake, irrespective of
whether the tb_switch_tmu_rate_write() API was successful or not.

However, this caused a problem with Thunderbolt 3 (TBT3)
devices, as the TSPacketInterval bits were always enabled by default,
leading the host router to assume that the device router's TMU was
already enabled and preventing it from initiating the Time
Synchronization Handshake. As a result, TBT3 monitors experienced
display flickering from the second hot plug onwards.

To address this issue, we have modified the code to only disable the
Time Synchronization Handshake during TMU disable if the
tb_switch_tmu_rate_write() function is successful. This ensures that
the TBT3 devices function correctly and eliminates the display
flickering issue.

Co-developed-by: Sanath S <Sanath.S@amd.com>
Signed-off-by: Sanath S <Sanath.S@amd.com>
Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[ USB4v2 introduced support for uni-directional TMU mode as part of
  d49b4f043d ("thunderbolt: Add support for enhanced uni-directional TMU mode")
  This is not a stable candidate commit, so adjust the code for backport. ]
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-30 16:11:11 +02:00
2023-08-30 16:11:10 +02:00
2023-08-30 16:11:08 +02:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2023-08-27 21:01:32 +02:00

Linux kernel
============

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There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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