Michał Mirosław [off-list ref] writes:

On Mon, Jan 20, 2020 at 09:06:18AM +0300, Sergey Organov wrote:

quoted

Michał Mirosław [off-list ref] writes:

quoted

On Fri, Jan 17, 2020 at 08:29:33AM +0300, Sergey Organov wrote:

quoted

--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c

@@ -563,6 +563,8 @@ static int gs_start_io(struct gs_port *port)
 
        /* unblock any pending writes into our circular buffer */
        if (started) {
+               pr_debug("gs_start_tx: ttyGS%d\n", port->port_num);
+               gs_start_tx(port);
                tty_wakeup(port->port.tty);

The tty_wakeup() will be called from gs_start_tx(), so should be removed
from here.

Not exactly. tty_wakeup() will be called from gs_start_tx() only when
there has been something actually transferred from the buffer. I didn't
want to change behavior when the buffer is empty, so I kept the explicit
tty_wakeup() call in place, intentionally. Please let me know if you
still think it should be removed.

Indeed it is as you describe. You might add an argument that initializes
do_tty_wake, but I'm not sure saving one tty_wakeup() on open is worth
the trouble.

OK, so let's leave it as is, at least for now.

quoted

quoted

The pr_debug() in other callers of gs_start_tx() say:
"caller: start ttyGS%d".

???

$ git co gregkh/tty-next && grep -r 'caller: start tty' .
HEAD is now at 7788f54... serial_core: Remove unused member in uart_port
$ 

Replace 'caller' with a function calling gs_start_io().

Thanks, now I see... Do you prefer:

   pr_debug("gs_start_io: start Tx on ttyGS%d\n", port->port_num);

then?

Alternatively, I'm OK with removing this new debug print.

What do you think?

Thanks,
-- Sergey Organov