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USB: serial: xr: fix B0 handling 

Fix up B0 handling which should leave the baud rate unchanged and
specifically not report back a non-B0 rate when B0 is requested; must
temporarily disable hardware flow control so that RTS can be deasserted;
and should reassert DTR/RTS when moving from B0.

Fixes: c2d405aa86 ("USB: serial: add MaxLinear/Exar USB to Serial driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2021-01-21 11:29:22 +01:00
parent 0d05d7d913
commit 55317e2239
1 changed files with 14 additions and 9 deletions
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23
drivers/usb/serial/xr_serial.c
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@ -341,8 +341,11 @@ static int xr_set_baudrate(struct tty_struct *tty,
u16 tx_mask, rx_mask;
int ret;
baud = clamp(tty->termios.c_ospeed, XR21V141X_MIN_SPEED,
XR21V141X_MAX_SPEED);
baud = tty->termios.c_ospeed;
if (!baud)
return 0;
baud = clamp(baud, XR21V141X_MIN_SPEED, XR21V141X_MAX_SPEED);
divisor = XR_INT_OSC_HZ / baud;
idx = ((32 * XR_INT_OSC_HZ) / baud) & 0x1f;
tx_mask = xr21v141x_txrx_clk_masks[idx].tx;
@ -399,7 +402,8 @@ static int xr_set_baudrate(struct tty_struct *tty,
}
static void xr_set_flow_mode(struct tty_struct *tty,
struct usb_serial_port *port)
struct usb_serial_port *port,
struct ktermios *old_termios)
{
u8 flow, gpio_mode;
int ret;
@ -411,7 +415,7 @@ static void xr_set_flow_mode(struct tty_struct *tty,
/* Set GPIO mode for controlling the pins manually by default. */
gpio_mode &= ~XR21V141X_UART_MODE_GPIO_MASK;
if (C_CRTSCTS(tty)) {
if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) {
dev_dbg(&port->dev, "Enabling hardware flow ctrl\n");
gpio_mode |= XR21V141X_UART_MODE_RTS_CTS;
flow = XR21V141X_UART_FLOW_MODE_HW;
@ -438,6 +442,11 @@ static void xr_set_flow_mode(struct tty_struct *tty,
xr_uart_enable(port);
xr_set_reg_uart(port, XR21V141X_REG_GPIO_MODE, gpio_mode);
if (C_BAUD(tty) == B0)
xr_dtr_rts(port, 0);
else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
xr_dtr_rts(port, 1);
}
static void xr_set_termios(struct tty_struct *tty,
@ -493,11 +502,7 @@ static void xr_set_termios(struct tty_struct *tty,
if (ret)
return;
/* If baud rate is B0, clear DTR and RTS */
if (C_BAUD(tty) == B0)
xr_dtr_rts(port, 0);
xr_set_flow_mode(tty, port);
xr_set_flow_mode(tty, port, old_termios);
}
static int xr_open(struct tty_struct *tty, struct usb_serial_port *port)