linux-kernel - [PATCH] usb: dwc3: Allow usb role swich control from userspace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20251020113723.553843-1-pritam.sutar@samsung.com>
Date: Mon, 20 Oct 2025 17:07:23 +0530
From: Pritam Manohar Sutar <pritam.sutar@...sung.com>
To: Thinh.Nguyen@...opsys.com, gregkh@...uxfoundation.org
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	rosa.pila@...sung.com, dev.tailor@...sung.com, faraz.ata@...sung.com,
	muhammed.ali@...sung.com, selvarasu.g@...sung.com, Pritam Manohar Sutar
	<pritam.sutar@...sung.com>
Subject: [PATCH] usb: dwc3: Allow usb role swich control from userspace

There is a possibility of user needs for USB mode switching on boards
that lack external hardware support for dynamic host/device role
detection.

Add an `allow_userspace_control` flag to handle such cases. When
enabled, it exposes a sysfs attribute that allows userspace to switch
the USB role manually between host and device. This provides flexibility
for platforms that cannot rely on hardware-based mode detection.

The role switch can be done as below
echo host > /sys/class/usb_role/<ADDR>.usb-role-switch/role
echo device > /sys/class/usb_role/<ADDR>.usb-role-switch/role

Signed-off-by: Pritam Manohar Sutar <pritam.sutar@...sung.com>
---
 drivers/usb/dwc3/drd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index 4c91240eb429..589bbeb27454 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -515,6 +515,7 @@ static int dwc3_setup_role_switch(struct dwc3 *dwc)
 	dwc3_role_switch.set = dwc3_usb_role_switch_set;
 	dwc3_role_switch.get = dwc3_usb_role_switch_get;
 	dwc3_role_switch.driver_data = dwc;
+	dwc3_role_switch.allow_userspace_control = true;
 	dwc->role_sw = usb_role_switch_register(dwc->dev, &dwc3_role_switch);
 	if (IS_ERR(dwc->role_sw))
 		return PTR_ERR(dwc->role_sw);
-- 
2.34.1