On Wed, Feb 06, 2019 at 09:56:15AM +0100, Johanna Abrahamsson wrote:
> From: Johanna Abrahamsson <johanna.abrahamsson@xxxxxxxxxxxxx>
>
> This patch adds minimum baud rate to the cp210x driver.
>
> According to the datasheet for CP2105, the SCI supports 2400 as the
> lowest baud rate. As this is not heeded in the current code, an error
> message 'failed set req 0x1e size 4 status: -32' when trying to set a
> lower baud rate such as 300.
> The other cp210x models to date supports a minimum baud rate of 300.
>
> Signed-off-by: Johanna Abrahamsson <johanna.abrahamsson@xxxxxxxxxxxxx>
> ---
Thanks for the update.
Now applied with a few minor tweaks:
> drivers/usb/serial/cp210x.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
> index 260c875dd263..ceff735e961c 100644
> --- a/drivers/usb/serial/cp210x.c
> +++ b/drivers/usb/serial/cp210x.c
> @@ -245,6 +245,7 @@ struct cp210x_serial_private {
> u8 gpio_input;
> #endif
> u8 partnum;
> + speed_t min_speed;
> speed_t max_speed;
> bool use_actual_rate;
> };
> @@ -1078,8 +1079,6 @@ static speed_t cp210x_get_actual_rate(struct usb_serial *serial, speed_t baud)
> unsigned int prescale = 1;
> unsigned int div;
>
> - baud = clamp(baud, 300u, priv->max_speed);
priv is now unused in this function and thus triggered a compilation
warning. I dropped priv along with the serial pointer.
> -
> if (baud <= 365)
> prescale = 4;
>
> @@ -1122,7 +1121,7 @@ static void cp210x_change_speed(struct tty_struct *tty,
> struct cp210x_serial_private *priv = usb_get_serial_data(serial);
> u32 baud;
>
> - baud = tty->termios.c_ospeed;
> + baud = clamp(tty->termios.c_ospeed, priv->min_speed, priv->max_speed);
I moved this clamp after the comment since this construct now makes sure
we honour max_speed.
> /*
> * This maps the requested rate to the actual rate, a valid rate on
> @@ -1134,8 +1133,6 @@ static void cp210x_change_speed(struct tty_struct *tty,
> baud = cp210x_get_actual_rate(serial, baud);
> else if (baud < 1000000)
> baud = cp210x_get_an205_rate(baud);
> - else if (baud > priv->max_speed)
> - baud = priv->max_speed;
>
> dev_dbg(&port->dev, "%s - setting baud rate to %u\n", __func__, baud);
> if (cp210x_write_u32_reg(port, CP210X_SET_BAUDRATE, baud)) {
> @@ -1797,28 +1794,35 @@ static void cp210x_init_max_speed(struct usb_serial *serial)
> {
> struct cp210x_serial_private *priv = usb_get_serial_data(serial);
> bool use_actual_rate = false;
> + speed_t min;
And I initialised min to 300 here which allows most initialisations
below to be removed.
> speed_t max;
>
> switch (priv->partnum) {
> case CP210X_PARTNUM_CP2101:
> + min = 300;
> max = 921600;
> break;
> case CP210X_PARTNUM_CP2102:
> case CP210X_PARTNUM_CP2103:
> + min = 300;
> max = 1000000;
> break;
> case CP210X_PARTNUM_CP2104:
> use_actual_rate = true;
> + min = 300;
> max = 2000000;
> break;
> case CP210X_PARTNUM_CP2108:
> + min = 300;
> max = 2000000;
> break;
> case CP210X_PARTNUM_CP2105:
> if (cp210x_interface_num(serial) == 0) {
> use_actual_rate = true;
> + min = 300;
> max = 2000000; /* ECI */
> } else {
> + min = 2400;
> max = 921600; /* SCI */
> }
> break;
> @@ -1826,13 +1830,16 @@ static void cp210x_init_max_speed(struct usb_serial *serial)
> case CP210X_PARTNUM_CP2102N_QFN24:
> case CP210X_PARTNUM_CP2102N_QFN20:
> use_actual_rate = true;
> + min = 300;
> max = 3000000;
> break;
> default:
> + min = 300;
> max = 2000000;
> break;
> }
>
> + priv->min_speed = min;
> priv->max_speed = max;
> priv->use_actual_rate = use_actual_rate;
> }
Thanks,
Johan
