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Dave Carey
f58752ebcb
The Lenovo Yoga Book 9 14IAH10 (83KJ) has a composite USB device (17EF:6161) that controls both touchscreens via a CDC ACM interface. Interface 0 is a standard CDC ACM control interface, but interface 1 (the data interface) incorrectly declares vendor-specific class (0xFF) instead of USB_CLASS_CDC_DATA. cdc-acm rejects the device at probe with -EINVAL, leaving interface 0 unbound and EP 0x82 never polled. With no consumer polling EP 0x82, the firmware's watchdog fires every ~20 seconds and resets the USB bus, producing a continuous disconnect/ reconnect loop that prevents the touchscreens from ever initialising. Add two new quirk flags: VENDOR_CLASS_DATA_IFACE: Bypasses the bInterfaceClass check in acm_probe() that would otherwise reject the vendor-class data interface with -EINVAL. ALWAYS_POLL_CTRL: Submits the notification URB at probe() rather than waiting for a TTY open. This keeps EP 0x82 polled at all times, permanently suppressing the firmware watchdog. The URB is resubmitted after port_shutdown() and on system resume. SET_CONTROL_LINE_STATE (DTR|RTS) is sent at probe and after port_shutdown() to complete firmware handshake. Note: the firmware performs exactly 4 USB connect/disconnect cycles (~19 s each) on every cold boot before stabilising. This is a fixed firmware property; touch is available ~75-80 s after power-on. Signed-off-by: Dave Carey <carvsdriver@gmail.com> Cc: stable <stable@kernel.org> Tested-by: Dave Carey <carvsdriver@gmail.com> Acked-by: Oliver Neukum <oneukum@suse.com> Link: https://patch.msgid.link/20260402182950.389016-1-carvsdriver@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>