Down the call stack from the ioctl handler for VIDIOC_STREAMON, uvc_video_alloc_requests contains a BUG_ON, which in the high level, triggers when VIDIOC_STREAMON ioctl is issued without VIDIOC_STREAMOFF being issued previously. This can happen in a few ways, such as if the userspace uvc gadget application simply doesn't issue VIDIOC_STREAMOFF. Another way is if uvc_function_set_alt with alt 0 is called after it is called with 1 but before VIDIOC_STREAMON is called; in this case, UVC_EVENT_STREAMOFF will not be queued to userspace, and therefore userspace will never call VIDIOC_STREAMOFF. To fix this, add two more uvc states: starting and stopping. The starting state is entered when uvc_function_set_alt 1 is called, and is exited in uvc_v4l2_streamon, when the state is changed to streaming. The stopping state is entered when uvc_function_set_alt 0 is called, and is exited in uvc_v4l2_streamoff, when the state is changed to connected. The status phase of the SET_INTERFACE request doesn't need to be delayed by the uvc gadget driver, so that is removed. Finally, there is another way to trigger the aforementioned BUG: start streaming and (physically) disconnect usb. To fix this, call uvcg_video_enable 0 in uvc_function_disable. Changes in v2: 1. Remove delay usb status phase Paul Elder (3): usb: gadget: uvc: synchronize streamon/off with uvc_function_set_alt usb: gadget: uvc: remove delay usb status phase from uvc usb: gadget: uvc: disable stream when disconnected drivers/usb/gadget/function/f_uvc.c | 14 +++++++++++--- drivers/usb/gadget/function/uvc.h | 2 ++ drivers/usb/gadget/function/uvc_v4l2.c | 21 +++++++++++++++------ 3 files changed, 28 insertions(+), 9 deletions(-) -- 2.17.0 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
