Updates the Connection Manager to disable the Gen 4 Link Recovery
flow before transitioning from a Symmetric Link to an Asymmetric
Link, as specified in recent changes to the USB4 v2 specification.
According to the "USB4 2.0 ENGINEERING CHANGE NOTICE FORM"
published in September 2024, the rationale for this change is:
"Since the default value of the Target Asymmetric Link might be
different than Symmetric Link and Gen 4 Link Recovery flow checks
this field to make sure it matched the actual Negotiated Link Width,
we’re removing the condition for a Disconnect in the Gen 4 Link
Recovery flow when Target Asymmetric Link doesn’t match the actual
Link width and adding a Connection Manager note to Disable Gen 4 Link
Recovery flow before doing Asymmetric Transitions."
Signed-off-by: Mohammad Rahimi <rahimi.mhmmd@xxxxxxxxx>
---
drivers/thunderbolt/tb.c | 28 +++++++++++++++++--
drivers/thunderbolt/tb.h | 3 ++
drivers/thunderbolt/tb_regs.h | 1 +
drivers/thunderbolt/usb4.c | 52 +++++++++++++++++++++++++++++++++++
4 files changed, 81 insertions(+), 3 deletions(-)
diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index a7c6919fbf97..31a8269a5156 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -1013,6 +1013,7 @@ static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
struct tb_port *dst_port, int requested_up,
int requested_down)
{
+ bool link_recovery_up = false, link_recovery_down = false;
bool clx = false, clx_disabled = false, downstream;
struct tb_switch *sw;
struct tb_port *up;
@@ -1075,15 +1076,29 @@ static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
continue;
/*
- * Disable CL states before doing any transitions. We
- * delayed it until now that we know there is a real
- * transition taking place.
+ * Disable CL states and Link Recovery flow before doing any
+ * transitions. We delayed it until now that we know there is
+ * a real transition taking place.
*/
if (!clx_disabled) {
clx = tb_disable_clx(sw);
clx_disabled = true;
}
+ ret = usb4_port_link_recovery_disable(up);
+ if (ret < 0) {
+ tb_port_warn(up, "failed to disable the link recovery\n");
+ break;
+ }
+ link_recovery_up = ret > 0;
+
+ ret = usb4_port_link_recovery_disable(down);
+ if (ret < 0) {
+ tb_port_warn(down, "failed to disable the link recovery\n");
+ break;
+ }
+ link_recovery_down = ret > 0;
+
tb_sw_dbg(up->sw, "configuring asymmetric link\n");
/*
@@ -1091,6 +1106,13 @@ static int tb_configure_asym(struct tb *tb, struct tb_port *src_port,
* transtion the link into asymmetric now.
*/
ret = tb_switch_set_link_width(up->sw, width_up);
+
+ /* Re-enable Link Recovery flow if they were previosly enabled */
+ if (link_recovery_up)
+ usb4_port_link_recovery_enable(up);
+ if (link_recovery_down)
+ usb4_port_link_recovery_enable(down);
+
if (ret) {
tb_sw_warn(up->sw, "failed to set link width\n");
break;
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index ddbf0cd78377..d37d778082fc 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1332,6 +1332,9 @@ int usb4_port_router_online(struct tb_port *port);
int usb4_port_enumerate_retimers(struct tb_port *port);
bool usb4_port_clx_supported(struct tb_port *port);
+int usb4_port_link_recovery_enable(struct tb_port *port);
+int usb4_port_link_recovery_disable(struct tb_port *port);
+
bool usb4_port_asym_supported(struct tb_port *port);
int usb4_port_asym_set_link_width(struct tb_port *port, enum tb_link_width width);
int usb4_port_asym_start(struct tb_port *port);
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 4e43b47f9f11..085139e1a958 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -398,6 +398,7 @@ struct tb_regs_port_header {
#define PORT_CS_19_WOD BIT(17)
#define PORT_CS_19_WOU4 BIT(18)
#define PORT_CS_19_START_ASYM BIT(24)
+#define PORT_CS_19_ELR BIT(31)
/* Display Port adapter registers */
#define ADP_DP_CS_0 0x00
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index e51d01671d8e..99fd6aa1704e 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -10,6 +10,7 @@
#include <linux/delay.h>
#include <linux/ktime.h>
#include <linux/units.h>
+#include <linux/string_helpers.h>
#include "sb_regs.h"
#include "tb.h"
@@ -1518,6 +1519,57 @@ bool usb4_port_clx_supported(struct tb_port *port)
return !!(val & PORT_CS_18_CPS);
}
+static int __usb4_port_link_recovery_enable(struct tb_port *port, bool enable)
+{
+ bool was_enable;
+ int ret;
+ u32 val;
+
+ ret = tb_port_read(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+ if (ret)
+ return ret;
+
+ was_enable = !!(val & PORT_CS_19_ELR);
+
+ if (enable)
+ val |= PORT_CS_19_ELR;
+ else
+ val &= ~PORT_CS_19_ELR;
+
+ ret = tb_port_write(port, &val, TB_CFG_PORT,
+ port->cap_usb4 + PORT_CS_19, 1);
+ if (ret)
+ return ret;
+
+ tb_port_dbg(port, "link recovery %s\n", str_enabled_disabled(enable));
+ return was_enable ? 1 : 0;
+}
+
+/**
+ * usb4_port_link_recovery_enable() - Enable the Link Recovery
+ * @port: USB4 port
+ *
+ * Enables the Link Recovery for @port.
+ * Returns -ERRNO on failure, otherwise the previous state of the Link Recovery.
+ */
+int usb4_port_link_recovery_enable(struct tb_port *port)
+{
+ return __usb4_port_link_recovery_enable(port, true);
+}
+
+/**
+ * usb4_port_link_recovery_disable() - Disable the Link Recovery
+ * @port: USB4 port
+ *
+ * Disables the Link Recovery for @port.
+ * Returns -ERRNO on failure, otherwise the previous state of the Link Recovery.
+ */
+int usb4_port_link_recovery_disable(struct tb_port *port)
+{
+ return __usb4_port_link_recovery_enable(port, false);
+}
+
/**
* usb4_port_asym_supported() - If the port supports asymmetric link
* @port: USB4 port
--
2.45.2
