The patch below does not apply to the 6.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.4.y git checkout FETCH_HEAD git cherry-pick -x 583893a66d731f5da010a3fa38a0460e05f0149b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023081248-trapped-trade-824b@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 583893a66d731f5da010a3fa38a0460e05f0149b Mon Sep 17 00:00:00 2001 From: Sanjay R Mehta <sanju.mehta@xxxxxxx> Date: Wed, 2 Aug 2023 06:11:49 -0500 Subject: [PATCH] thunderbolt: Fix Thunderbolt 3 display flickering issue on 2nd hot plug onwards 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@xxxxxxx> Signed-off-by: Sanath S <Sanath.S@xxxxxxx> Signed-off-by: Sanjay R Mehta <sanju.mehta@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> diff --git a/drivers/thunderbolt/tmu.c b/drivers/thunderbolt/tmu.c index 1269f417515b..0dfd1e083994 100644 --- a/drivers/thunderbolt/tmu.c +++ b/drivers/thunderbolt/tmu.c @@ -579,7 +579,9 @@ int tb_switch_tmu_disable(struct tb_switch *sw) * uni-directional mode and we don't want to change it's TMU * mode. */ - tb_switch_tmu_rate_write(sw, tmu_rates[TB_SWITCH_TMU_MODE_OFF]); + ret = tb_switch_tmu_rate_write(sw, tmu_rates[TB_SWITCH_TMU_MODE_OFF]); + if (ret) + return ret; tb_port_tmu_time_sync_disable(up); ret = tb_port_tmu_time_sync_disable(down);
