linux-kernel - [PATCH AUTOSEL 5.18 01/56] thunderbolt: Change downstream router's TMU rate in both TMU uni/bidir mode

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Date:   Sun, 14 Aug 2022 11:29:31 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Gil Fine <gil.fine@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>, andreas.noever@...il.com,
        michael.jamet@...el.com, YehezkelShB@...il.com,
        linux-usb@...r.kernel.org
Subject: [PATCH AUTOSEL 5.18 01/56] thunderbolt: Change downstream router's TMU rate in both TMU uni/bidir mode

From: Gil Fine <gil.fine@...el.com>

[ Upstream commit 5fd6b9a5cbe63fea4c490fee8af34144a139a266 ]

In case of uni-directional time sync, TMU handshake is
initiated by upstream router. In case of bi-directional
time sync, TMU handshake is initiated by downstream router.
In order to handle correctly the case of uni-directional mode,
we avoid changing the upstream router's rate to off,
because it might have another downstream router plugged that is set to
uni-directional mode (and we don't want to change its mode).
Instead, we always change downstream router's rate.

Signed-off-by: Gil Fine <gil.fine@...el.com>
Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/thunderbolt/tmu.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/thunderbolt/tmu.c b/drivers/thunderbolt/tmu.c
index e4a07a26f693..93ba1d00335b 100644
--- a/drivers/thunderbolt/tmu.c
+++ b/drivers/thunderbolt/tmu.c
@@ -359,13 +359,14 @@ int tb_switch_tmu_disable(struct tb_switch *sw)
 		 * In case of uni-directional time sync, TMU handshake is
 		 * initiated by upstream router. In case of bi-directional
 		 * time sync, TMU handshake is initiated by downstream router.
-		 * Therefore, we change the rate to off in the respective
-		 * router.
+		 * We change downstream router's rate to off for both uni/bidir
+		 * cases although it is needed only for the bi-directional mode.
+		 * We avoid changing upstream router's mode since it might
+		 * have another downstream router plugged, that is set to
+		 * uni-directional mode and we don't want to change it's TMU
+		 * mode.
 		 */
-		if (unidirectional)
-			tb_switch_tmu_rate_write(parent, TB_SWITCH_TMU_RATE_OFF);
-		else
-			tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);
+		tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);
 
 		tb_port_tmu_time_sync_disable(up);
 		ret = tb_port_tmu_time_sync_disable(down);
-- 
2.35.1