linux-kernel - [PATCH 1/2] thunderbolt: Explicitly reset plug events delay back to USB4 spec value

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Message-ID: <20220921145434.21659-2-mario.limonciello@amd.com>
Date:   Wed, 21 Sep 2022 09:54:32 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        "Yehezkel Bernat" <YehezkelShB@...il.com>
CC:     <sanju.mehta@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] thunderbolt: Explicitly reset plug events delay back to USB4 spec value

If any software has interacted with the USB4 registers before the Linux
USB4 CM runs, it may have modified the plug events delay. It has been
observed that if this value too large, it's possible that hotplugged
devices will negotiate a fallback mode instead in Linux.

To prevent this, explicitly align the plug events delay with the USB4
spec value of 10ms.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 drivers/thunderbolt/switch.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index c63c1f4ff9dc..77d7f07ca075 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -2413,6 +2413,7 @@ int tb_switch_configure(struct tb_switch *sw)
 		 * additional capabilities.
 		 */
 		sw->config.cmuv = USB4_VERSION_1_0;
+		sw->config.plug_events_delay = 0xa;
 
 		/* Enumerate the switch */
 		ret = tb_sw_write(sw, (u32 *)&sw->config + 1, TB_CFG_SWITCH,
-- 
2.34.1