From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: linux-usb@vger.kernel.org
Cc: Yehezkel Bernat <YehezkelShB@gmail.com>,
Lukas Wunner <lukas@wunner.de>,
Andreas Noever <andreas.noever@gmail.com>,
Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>,
Pooja Katiyar <pooja.katiyar@intel.com>,
Rene Sapiens <rene.sapiens@linux.intel.com>,
Gil Fine <gil.fine@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: [PATCH 8/8] thunderbolt: Increase Notification Timeout to 255 ms for USB4 routers
Date: Tue, 12 May 2026 14:29:55 +0200 [thread overview]
Message-ID: <20260512122955.271688-9-mika.westerberg@linux.intel.com> (raw)
In-Reply-To: <20260512122955.271688-1-mika.westerberg@linux.intel.com>
From: Gil Fine <gil.fine@linux.intel.com>
Currently we set the Notification Timeout field in ROUTER_CS_4 for USB4
routers to 10 ms, which is unnecessarily short and may cause unnecessary
retransmissions of Hot Plug packets by the router in case of slow
software response.
Increase the timeout to 255 ms, aligning with Thunderbolt 3 routers
and providing adequate time for software to process Hot Plug Events.
While there, fix the comment describing the Notification Timeout
field to match the USB4 specification.
Signed-off-by: Gil Fine <gil.fine@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/thunderbolt/switch.c | 12 +++---------
drivers/thunderbolt/tb_regs.h | 3 +--
2 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index f421997c298d..d7c53eb3221b 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -1767,8 +1767,6 @@ int tb_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
/*
* tb_plug_events_active() - enable/disable plug events on a switch
*
- * Also configures a sane plug_events_delay of 255ms.
- *
* Return: %0 on success, negative errno otherwise.
*/
static int tb_plug_events_active(struct tb_switch *sw, bool active)
@@ -1779,11 +1777,6 @@ static int tb_plug_events_active(struct tb_switch *sw, bool active)
if (tb_switch_is_icm(sw) || tb_switch_is_usb4(sw))
return 0;
- sw->config.plug_events_delay = 0xff;
- res = tb_sw_write(sw, ((u32 *) &sw->config) + 4, TB_CFG_SWITCH, 4, 1);
- if (res)
- return res;
-
res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
if (res)
return res;
@@ -2645,6 +2638,8 @@ int tb_switch_configure(struct tb_switch *sw)
sw->config.enabled = 1;
+ /* Set Notification Timeout to 255 ms for all routers */
+ sw->config.plug_events_delay = 0xff;
if (tb_switch_is_usb4(sw)) {
/*
* For USB4 devices, we need to program the CM version
@@ -2656,7 +2651,6 @@ int tb_switch_configure(struct tb_switch *sw)
sw->config.cmuv = ROUTER_CS_4_CMUV_V1;
else
sw->config.cmuv = ROUTER_CS_4_CMUV_V2;
- sw->config.plug_events_delay = 0xa;
/* Enumerate the switch */
ret = tb_sw_write(sw, (u32 *)&sw->config + 1, TB_CFG_SWITCH,
@@ -2677,7 +2671,7 @@ int tb_switch_configure(struct tb_switch *sw)
/* Enumerate the switch */
ret = tb_sw_write(sw, (u32 *)&sw->config + 1, TB_CFG_SWITCH,
- ROUTER_CS_1, 3);
+ ROUTER_CS_1, 4);
}
if (ret)
return ret;
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
index 69ca4c379cc9..92d893634d2b 100644
--- a/drivers/thunderbolt/tb_regs.h
+++ b/drivers/thunderbolt/tb_regs.h
@@ -182,8 +182,7 @@ struct tb_regs_switch_header {
/* DWORD 4 */
u32 plug_events_delay:8; /*
* RW, pause between plug events in
- * milliseconds. Writing 0x00 is interpreted
- * as 255ms.
+ * milliseconds.
*/
u32 cmuv:8;
u32 __unknown4:8;
--
2.50.1
prev parent reply other threads:[~2026-05-12 12:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 12:29 [PATCH 0/8] thunderbolt: Make the driver follow CM guide more closely Mika Westerberg
2026-05-12 12:29 ` [PATCH 1/8] thunderbolt: Improve multi-display DisplayPort tunnel allocation Mika Westerberg
2026-05-12 12:29 ` [PATCH 2/8] thunderbolt: Don't access path config space on Lane 1 adapters in tb_switch_reset_host() Mika Westerberg
2026-05-12 12:29 ` [PATCH 3/8] thunderbolt: Fix lane bonding log when bonding not possible Mika Westerberg
2026-05-12 12:29 ` [PATCH 4/8] thunderbolt: Activate path hops from source to destination Mika Westerberg
2026-05-12 12:29 ` [PATCH 5/8] thunderbolt: Verify PCIe adapter in detect state before tunnel setup Mika Westerberg
2026-05-12 12:29 ` [PATCH 6/8] thunderbolt: Verify Router Ready bit is set after router enumeration Mika Westerberg
2026-05-12 12:29 ` [PATCH 7/8] thunderbolt: Increase timeout for Configuration Ready bit Mika Westerberg
2026-05-12 12:29 ` Mika Westerberg [this message]
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