staging: greybus: uart: clean up TIOCGSERIAL

TIOCSSERIAL is a horrid, underspecified, legacy interface which for most
serial devices is only useful for setting the close_delay and
closing_wait parameters.

The xmit_fifo_size parameter could be used to set the hardware transmit
fifo size of a legacy UART when it could not be detected, but the
interface is limited to eight bits and should be left unset when not
used.

Similarly, baud_base could be used to set the UART base clock when it
could not be detected but might as well be left unset when it is not
known.

The type parameter could be used to set the UART type, but is
better left unspecified (type unknown) when it isn't used.

Note that some applications have historically expected TIOCGSERIAL to be
implemented, but judging from the Debian sources, the port type not
being PORT_UNKNOWN is only used to check for the existence of legacy
serial ports (ttySn). Notably USB serial drivers like ftdi_sio have been
using PORT_UNKNOWN for twenty years without any problems.

Drop the bogus values provided by the greybus implementation.

Signed-off-by: Johan Hovold <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index a520f7f213db028973c897d38113b03ff9a656a9..b1e63f7798b02e7ef25a55194686bf6a7c7a7aae 100644 (file)
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -610,10 +610,7 @@ static int get_serial_info(struct tty_struct *tty,
 {
        struct gb_tty *gb_tty = tty->driver_data;
 
-       ss->type = PORT_16550A;
        ss->line = gb_tty->minor;
-       ss->xmit_fifo_size = 16;
-       ss->baud_base = 9600;
        ss->close_delay = jiffies_to_msecs(gb_tty->port.close_delay) / 10;
        ss->closing_wait =
                gb_tty->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ?