On Sun, Apr 24, 2016 at 12:09:21PM -0500, Konstantin Shkolnyy wrote:
> Documented "magic numbers" used in the CRTSCT flag code in terms of
> register bit names from the chip specification.
Documenting these is long overdue. I even started adding defines just to
be able to review the first patch in the series.
> Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@xxxxxxxxx>
> ---
> 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 */
But instead of adding comments like this one and below, please add
proper defines for the various flags and masks. That will make the code
mostly self-explanatory.
> 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[7] = 0;
> + modem_ctl[7] = 0; /* SERIAL_XOFF_CONTINUE = 0 */
And this would be better as a bit operation as well (as already
mentioned).
Thanks,
Johan
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