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An asynchronous vbus_event_work() keep running when switch the role from
device to host. This affects EHCI host controller initialization.
USBCMD.RUNSTOP bit is set at ehci_run() and cleared by following
vbus_event_work() if bus_event_work() run after ehci_run().
The log below shows what happens:
[ 87.819925] ci_hdrc ci_hdrc.0: EHCI Host Controller
[ 87.819963] ci_hdrc ci_hdrc.0: new USB bus registered, assigned bus number 1
[ 87.955634] ci_hdrc ci_hdrc.0: USB 2.0, controller refused to start: -110
[ 87.955658] ci_hdrc ci_hdrc.0: startup error -110
[ 87.955682] ci_hdrc ci_hdrc.0: USB bus 1 deregistered
The problem is that the chipidea UDC driver call usb_udc_vbus_handler() to
pull down data line but it don't wait for completion before host controller
starts running.
Now UDC core can properly delete usb gadget device and make sure that vbus
work is cancelled or completed after usb_del_gadget_udc() is returned. But
the udc.c only call usb_del_gadget_udc() in ci_hdrc_gadget_destroy(). To
avoid above issue, add/remove the gadget device dynamically during USB role
switching.
To support dynamic gadget add/remove, do below steps:
- clear ci->gadget and ci->ci_hw_ep at initialization.
- assign udc_[start|stop]() to rdrv->[start|stop] and properly merge the
operations in udc_id_switch_for_[device|host]() to udc_[start|stop]()
Adjust the order ci_handle_vbus_change() and ci_role_start() to avoid NULL
pointer reference since ci_hdrc_gadget_init() doesn't add gadget anymore.
Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://patch.msgid.link/20260427075653.3611180-2-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. 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