[PATCH v3 6/6] thunderbolt: Change TMU mode to HiFi uni-directional once DisplayPort tunneled

Gil Fine
2022-05-11T13:56:51Z

Here we configure TMU mode to HiFi uni-directional once DP tunnel
is created. This is due to accuracy requirement for DP tunneling
as appears in CM guide 1.0, section 7.3.2.
Due to Intel hardware limitation, once we changed the TMU mode to HiFi
uni-directional (when DP tunnel exists), we don't change TMU mode back to
normal uni-directional, even if DP tunnel is torn down later.

Signed-off-by: Gil Fine <gil.fine@intel.com>
---
drivers/thunderbolt/tb.c | 28 ++++++++++++++++++++++++++++
drivers/thunderbolt/tb.h | 5 +++++
drivers/thunderbolt/tmu.c | 14 ++++++++++++++
3 files changed, 47 insertions(+)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index f512197e719b..d0f85a8c56de 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -50,6 +50,8 @@ struct tb_hotplug_event {
};

static void tb_handle_hotplug(struct work_struct *work);
+static void tb_enable_tmu_1st_child(struct tb *tb,
+ enum tb_switch_tmu_rate rate);

static void tb_queue_hotplug(struct tb *tb, u64 route, u8 port, bool unplug)
{
@@ -118,6 +120,13 @@ static void tb_switch_discover_tunnels(struct tb_switch *sw,
switch (port->config.type) {
case TB_TYPE_DP_HDMI_IN:
tunnel = tb_tunnel_discover_dp(tb, port, alloc_hopids);
+ /*
+ * In case of DP tunnel exists, change TMU mode to
+ * HiFi for CL0s to work.
+ */
+ if (tunnel)
+ tb_enable_tmu_1st_child(tb,
+ TB_SWITCH_TMU_RATE_HIFI);
break;

case TB_TYPE_PCIE_DOWN:
@@ -235,6 +244,19 @@ static int tb_enable_tmu(struct tb_switch *sw)
return tb_switch_tmu_enable(sw);
}

+/*
+ * Once a DP tunnel exists in the domain, we set the TMU mode so that
+ * it meets the accuracy requirements and also enables CLx entry (CL0s).
+ * We set the TMU mode of the first depth router(s) for CL0s to work.
+ */
+static void tb_enable_tmu_1st_child(struct tb *tb, enum tb_switch_tmu_rate rate)
+{
+ struct tb_sw_tmu_config tmu = { .rate = rate };
+
+ device_for_each_child(&tb->root_switch->dev, &tmu,
+ tb_switch_tmu_config_enable);
+}
+
/**
* tb_find_unused_port() - return the first inactive port on @sw
* @sw: Switch to find the port on
@@ -985,6 +1007,12 @@ static void tb_tunnel_dp(struct tb *tb)

list_add_tail(&tunnel->list, &tcm->tunnel_list);
tb_reclaim_usb3_bandwidth(tb, in, out);
+ /*
+ * In case of DP tunnel exists, change TMU mode to
+ * HiFi for CL0s to work.
+ */
+ tb_enable_tmu_1st_child(tb, TB_SWITCH_TMU_RATE_HIFI);
+
return;

err_free:
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index a16fffba9dd2..3dbd9d919d5f 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -110,6 +110,10 @@ struct tb_switch_tmu {
enum tb_switch_tmu_rate rate_request;
};

+struct tb_sw_tmu_config {
+ enum tb_switch_tmu_rate rate;
+};
+
enum tb_clx {
TB_CLX_DISABLE,
/* CL0s and CL1 are enabled and supported together */
@@ -934,6 +938,7 @@ int tb_switch_tmu_enable(struct tb_switch *sw);
void tb_switch_tmu_configure(struct tb_switch *sw,
enum tb_switch_tmu_rate rate,
bool unidirectional);
+int tb_switch_tmu_config_enable(struct device *dev, void *data);
/**
* tb_switch_tmu_is_enabled() - Checks if the specified TMU mode is enabled
* @sw: Router whose TMU mode to check
diff --git a/drivers/thunderbolt/tmu.c b/drivers/thunderbolt/tmu.c
index e822ab90338b..b8ff9f64a71e 100644
--- a/drivers/thunderbolt/tmu.c
+++ b/drivers/thunderbolt/tmu.c
@@ -727,6 +727,20 @@ int tb_switch_tmu_enable(struct tb_switch *sw)
return tb_switch_tmu_set_time_disruption(sw, false);
}

+int tb_switch_tmu_config_enable(struct device *dev, void *data)
+{
+ if (tb_is_switch(dev)) {
+ struct tb_switch *sw = tb_to_switch(dev);
+ struct tb_sw_tmu_config *tmu = data;
+
+ tb_switch_tmu_configure(sw, tmu->rate, tb_switch_is_clx_enabled(sw, TB_CL1));
+ if (tb_switch_tmu_enable(sw))
+ tb_sw_dbg(sw, "Fail switching TMU to HiFi for 1st depth router\n");
+ }
+
+ return 0;
+}
+
/**
* tb_switch_tmu_configure() - Configure the TMU rate and directionality
* @sw: Router whose mode to change
--
2.17.1