[PATCH v3 4/6] thunderbolt: Change downstream router's TMU rate in both TMU uni/bidir mode

Gil Fine
2022-05-11T13:56:50Z

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@intel.com>
---
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 b656659d02fb..985ca43b8f39 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);
--
2.17.1