Hi, On 11/30/2016 05:02 PM, Baolin Wang wrote: > If the hardware never responds to the stop endpoint command, the > URBs will never be completed, and we might hang the USB subsystem. > The original watchdog timer is used to watch if one stop endpoint > command is timeout, if timeout, then the watchdog timer will set > XHCI_STATE_DYING, try to halt the xHCI host, and give back all > pending URBs. > > But now we already have one command timer to control command timeout, > thus we can also use the command timer to watch the stop endpoint > command, instead of one duplicate watchdog timer which need to be > removed. > > Meanwhile we don't need the 'stop_cmds_pending' flag to identy if > this is the last stop endpoint command of one endpoint. Since we > can make sure we only set one stop endpoint command for one endpoint > by 'EP_HALT_PENDING' flag in xhci_urb_dequeue() function. Thus remove > this flag. I am afraid you can't do this. "stop_cmds_pending" was added to fix the problem described in the comments that you want to remove. But I didn't find any fix of this problem in your patch. - * The timer may also fire if the host takes a very long time to respond to the - * command, and the stop endpoint command completion handler cannot delete the - * timer before the timer function is called. Another endpoint cancellation may - * sneak in before the timer function can grab the lock, and that may queue - * another stop endpoint command and add the timer back. So we cannot use a - * simple flag to say whether there is a pending stop endpoint command for a - * particular endpoint. - * - * Instead we use a combination of that flag and a counter for the number of - * pending stop endpoint commands. If the timer is the tail end of the last - * stop endpoint command, and the endpoint's command is still pending, we assume - * the host is dying. Best regards, Lu Baolu > > We also need to clean up the command queue before trying to halt the > xHCI host in xhci_stop_endpoint_command_timeout() function. > > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx> -- 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
