[PATCH v8 7/8] usb: misc: qcom_eud: fix virtual attach/detach event handling
From: Elson Serrao <hidden>
Date: 2026-09-12 22:53:14
Also in:
linux-arm-msm, linux-usb, lkml
Subsystem:
arm/qualcomm mailing list, qcom embedded usb debugger (eud), the rest, usb subsystem · Maintainers:
Souradeep Chowdhury, Linus Torvalds, Greg Kroah-Hartman
EUD provides virtual USB attach/detach events to simulate cable plug/unplug while maintaining the physical debug connection. However, the current implementation incorrectly sets the USB role to HOST on virtual detach, which doesn't represent the disconnected state. Fix the virtual detach handling by setting the USB role to NONE instead of HOST, correctly representing the disconnected state. Reviewed-by: Konrad Dybcio <redacted> Reviewed-by: Peter Chen <peter.chen@kernel.org> Signed-off-by: Elson Serrao <redacted> --- drivers/usb/misc/qcom_eud.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
index 353c45dfd328..669e2e00dd7b 100644
--- a/drivers/usb/misc/qcom_eud.c
+++ b/drivers/usb/misc/qcom_eud.c@@ -313,10 +313,26 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data) if (!chip->enabled || path->curr_role != USB_ROLE_DEVICE) goto out; + /* + * EUD virtual attach/detach event handling for low power debugging: + * + * When EUD is enabled in debug mode, the device remains physically + * connected to the PC throughout the debug session, keeping the USB + * controller active. This prevents testing of low power scenarios that + * require USB disconnection. + * + * EUD solves this by providing virtual USB attach/detach events while + * maintaining the physical connection. These events are triggered from + * the Host PC via the enumerated EUD control interface and delivered + * to the EUD driver as interrupts. + * + * These notifications are forwarded to the USB controller through role + * switch framework. + */ if (chip->usb_attached) ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_DEVICE); else - ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_HOST); + ret = usb_role_switch_set_role(path->controller_sw, USB_ROLE_NONE); if (ret) dev_err(chip->dev, "failed to set role switch\n");
--
2.34.1