03.05.2013 20:30, Greg KH пишет:
We need some way to check the chars in the buffer, is the device you are using just very slow to respond to this request? How slow? Do you have a test case that we can see how it is affected?
Greg, unfortunately, I do have nothing. The customer is in CC list, so maybe he will provide the test-case, but I doubt. Please, what are your concerns here? The patch in question does this: --- + ret = usb_control_msg(port->serial->dev, + usb_rcvctrlpipe(port->serial->dev, 0), + FTDI_SIO_GET_MODEM_STATUS_REQUEST, + FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE, + 0, priv->interface, + buf, 2, WDR_TIMEOUT); --- Obviously, this is too expensive to call too frequently, or am I missing something? I asked the customer to comment out tty_chars_in_buffer(tty) < WAKEUP_CHARS line in n_tty.c, and he said that cured his problems, so I think my guess was right. The patch claims it only affects tcdrain() and close(). Its trivial to see it also affects poll(), select() and TIOCOUTQ ioctl, so even from that it is already broken. Why do you need a test-case for this? -- 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
