[PATCH] thunderbolt: Remove the TBT3 Not Supported bit

[PATCH] thunderbolt: Remove the TBT3 Not Supported bit

[Mohammad Rahimi]

Since USB4 v2 specification has removed the mandatory requirement to
support TBT3 on a USB4 Dock UFP, the TBT3 Not Supported bit is not
usable, as when it needs to be read there is no USB4 Link.

This change was introduced in a "USB4 2.0 ENGINEERING CHANGE NOTICE
FORM" published in September 2024, titled "TBT3 Support on USB4 Dock
UFP".

Signed-off-by: Mohammad Rahimi <rahimi.mhmmd@gmail.com>
---
 drivers/thunderbolt/tb_regs.h | 1 -
 drivers/thunderbolt/usb4.c    | 7 ++-----
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 4e43b47f9f11..7c5d27571b66 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -212,7 +212,6 @@ struct tb_regs_switch_header {
 #define ROUTER_CS_5_CV				BIT(31)
 #define ROUTER_CS_6				0x06
 #define ROUTER_CS_6_SLPR			BIT(0)
-#define ROUTER_CS_6_TNS				BIT(1)
 #define ROUTER_CS_6_WOPS			BIT(2)
 #define ROUTER_CS_6_WOUS			BIT(3)
 #define ROUTER_CS_6_HCI				BIT(18)
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index e51d01671d8e..e25a594649b2 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -241,8 +241,8 @@ int usb4_switch_setup(struct tb_switch *sw)
 {
 	struct tb_switch *parent = tb_switch_parent(sw);
 	struct tb_port *down;
-	bool tbt3, xhci;
 	u32 val = 0;
+	bool xhci;
 	int ret;
 
 	if (!tb_route(sw))
@@ -257,10 +257,7 @@ int usb4_switch_setup(struct tb_switch *sw)
 	tb_sw_dbg(sw, "link: %s\n", sw->link_usb4 ? "USB4" : "TBT");
 
 	xhci = val & ROUTER_CS_6_HCI;
-	tbt3 = !(val & ROUTER_CS_6_TNS);
-
-	tb_sw_dbg(sw, "TBT3 support: %s, xHCI: %s\n",
-		  tbt3 ? "yes" : "no", xhci ? "yes" : "no");
+	tb_sw_dbg(sw, "xHCI support: %s\n", xhci ? "yes" : "no");
 
 	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, ROUTER_CS_5, 1);
 	if (ret)
-- 
2.45.2

Re: [PATCH] thunderbolt: Remove the TBT3 Not Supported bit

[Mika Westerberg]

Hi,

On Mon, Feb 03, 2025 at 01:17:47AM +0000, Mohammad Rahimi wrote:
> Since USB4 v2 specification has removed the mandatory requirement to
> support TBT3 on a USB4 Dock UFP, the TBT3 Not Supported bit is not
> usable, as when it needs to be read there is no USB4 Link.
> 
> This change was introduced in a "USB4 2.0 ENGINEERING CHANGE NOTICE
> FORM" published in September 2024, titled "TBT3 Support on USB4 Dock
> UFP".

I think the USB4 v1 hardware still has this bit and since it is just
debugging there is no harm keeping it around.