Documented "magic numbers" used in the CRTSCT flag code in terms of register bit names from the chip specification.
Signed-off-by: Konstantin Shkolnyy <[email protected]> --- drivers/usb/serial/cp210x.c | 38 ++++++++++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 4 deletions(-) diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index ede5c52..b2321a7 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -790,7 +790,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port, cp210x_read_reg_block(port, CP210X_GET_FLOW, modem_ctl, sizeof(modem_ctl)); - if (modem_ctl[0] & 0x08) { + if (modem_ctl[0] & 0x08) { /* if SERIAL_CTS_HANDSHAKE */ dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__); cflag |= CRTSCTS; } else { @@ -952,17 +952,47 @@ static void cp210x_set_termios(struct tty_struct *tty, __func__, modem_ctl[0], modem_ctl[4], modem_ctl[7]); if (cflag & CRTSCTS) { - modem_ctl[0] &= ~0x7B; + modem_ctl[0] &= ~0x7B; /* keep reserved D2 and D7 */ + /* + * D1-D0 SERIAL_DTR_MASK =01b: DTR is held active + * D3 SERIAL_CTS_HANDSHAKE =1: CTS is a handshake line + * D4 SERIAL_DSR_HANDSHAKE =0 + * D5 SERIAL_DCD_HANDSHAKE =0 + * D6 SERIAL_DSR_SENSITIVITY =0 + */ modem_ctl[0] |= 0x09; + /* + * D0 SERIAL_AUTO_TRANSMIT =0 + * D1 SERIAL_AUTO_RECEIVE =0 + * D2 SERIAL_ERROR_CHAR =0 + * D3 SERIAL_NULL_STRIPPING =0 + * D4 SERIAL_BREAK_CHAR =0 + * D7-D6 SERIAL_RTS_MASK =10b: RTS for rcv flow control + */ modem_ctl[4] = 0x80; dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__); } else { - modem_ctl[0] &= ~0x7B; + modem_ctl[0] &= ~0x7B; /* keep reserved D2 and D7 */ + /* + * D1-D0 SERIAL_DTR_MASK = 01b: DTR is held active + * D3 SERIAL_CTS_HANDSHAKE = 0: CTS is a status input. + * D4 SERIAL_DSR_HANDSHAKE = 0 + * D5 SERIAL_DCD_HANDSHAKE = 0 + * D6 SERIAL_DSR_SENSITIVITY = 0 + */ modem_ctl[0] |= 0x01; + /* + * D0 SERIAL_AUTO_TRANSMIT = 0 + * D1 SERIAL_AUTO_RECEIVE = 0 + * D2 SERIAL_ERROR_CHAR = 0 + * D3 SERIAL_NULL_STRIPPING = 0 + * D4 SERIAL_BREAK_CHAR = 0 + * D7-D6 SERIAL_RTS_MASK =01b: RTS is statically active + */ modem_ctl[4] = 0x40; dev_dbg(dev, "%s - flow control = NONE\n", __func__); } - modem_ctl[7] = 0; + modem_ctl[7] = 0; /* SERIAL_XOFF_CONTINUE = 0 */ dev_dbg(dev, "%s - write modem controls = %02x .. .. .. %02x .. .. %02x\n", __func__, modem_ctl[0], modem_ctl[4], modem_ctl[7]); -- 1.8.4.5
