On 2/24/21 12:04 PM, Johan Hovold wrote:
> Perhaps you can even figure out how to poll for an empty TX FIFO from
> it, unless Charles is able to provide some details on that separate
> matter?
>
I presume from the code below, that when the device is closed, all data waiting to send is clobbered (if so, so the problem is the driver and not the device)
I would have thought that the driver should drain the buffers. I can see that this might be a problem if there is flow control (it may never drain) but the current method seems pretty brutal.
119 void usb_serial_generic_close(struct usb_serial_port *port)
120 {
121 unsigned long flags;
122 int i;
123
124 if (port->bulk_out_size) {
125 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
126 usb_kill_urb(port->write_urbs[i]);
127
128 spin_lock_irqsave(&port->lock, flags);
129 kfifo_reset_out(&port->write_fifo);
130 spin_unlock_irqrestore(&port->lock, flags);
131 }
132 if (port->bulk_in_size) {
133 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
134 usb_kill_urb(port->read_urbs[i]);
135 }
136 }
