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USB: serial: cp210x: suppress modem-control errors
The CP210X_SET_MHS request cannot be used to control RTS when hardware flow control (auto-RTS) is enabled and instead returns an error which is currently logged as: cp210x ttyUSB0: failed set request 0x7 status: -32 when opening and closing a port (and on TIOCMSET requests). Add a crtscts flag to keep track of the hardware flow-control setting and use it to suppress any request to change RTS when auto-RTS is enabled. Note that RTS is still deasserted when disabling the UART as part of close. Reported-by: Pho Tran <pho.tran@silabs.com> Signed-off-by: Johan Hovold <johan@kernel.org>
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parent
fea7372cbc
commit
5951b85088
1 changed files with 30 additions and 3 deletions
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@ -21,6 +21,7 @@
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#include <linux/usb/serial.h>
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#include <linux/gpio/driver.h>
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#include <linux/bitops.h>
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#include <linux/mutex.h>
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#define DRIVER_DESC "Silicon Labs CP210x RS232 serial adaptor driver"
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@ -265,6 +266,9 @@ struct cp210x_port_private {
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bool event_mode;
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enum cp210x_event_state event_state;
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u8 lsr;
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struct mutex mutex;
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bool crtscts;
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};
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static struct usb_serial_driver cp210x_device = {
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@ -1117,6 +1121,7 @@ static bool cp210x_termios_change(const struct ktermios *a, const struct ktermio
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static void cp210x_set_flow_control(struct tty_struct *tty,
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struct usb_serial_port *port, struct ktermios *old_termios)
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{
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struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
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struct cp210x_special_chars chars;
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struct cp210x_flow_ctl flow_ctl;
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u32 flow_repl;
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@ -1143,10 +1148,12 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
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return;
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}
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mutex_lock(&port_priv->mutex);
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ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl,
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sizeof(flow_ctl));
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if (ret)
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return;
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goto out_unlock;
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ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
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flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
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@ -1161,10 +1168,12 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
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ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE;
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flow_repl &= ~CP210X_SERIAL_RTS_MASK;
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flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_FLOW_CTL);
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port_priv->crtscts = true;
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} else {
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ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE;
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flow_repl &= ~CP210X_SERIAL_RTS_MASK;
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flow_repl |= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_ACTIVE);
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port_priv->crtscts = false;
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}
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if (I_IXOFF(tty))
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@ -1188,6 +1197,8 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
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cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
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sizeof(flow_ctl));
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out_unlock:
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mutex_unlock(&port_priv->mutex);
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}
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static void cp210x_set_termios(struct tty_struct *tty,
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@ -1272,7 +1283,9 @@ static int cp210x_tiocmset(struct tty_struct *tty,
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static int cp210x_tiocmset_port(struct usb_serial_port *port,
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unsigned int set, unsigned int clear)
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{
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struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
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u16 control = 0;
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int ret;
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if (set & TIOCM_RTS) {
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control |= CONTROL_RTS;
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@ -1291,9 +1304,22 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port,
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control |= CONTROL_WRITE_DTR;
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}
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mutex_lock(&port_priv->mutex);
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/*
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* SET_MHS cannot be used to control RTS when auto-RTS is enabled.
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* Note that RTS is still deasserted when disabling the UART on close.
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*/
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if (port_priv->crtscts)
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control &= ~CONTROL_WRITE_RTS;
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dev_dbg(&port->dev, "%s - control = 0x%.4x\n", __func__, control);
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return cp210x_write_u16_reg(port, CP210X_SET_MHS, control);
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ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control);
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mutex_unlock(&port_priv->mutex);
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return ret;
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}
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static void cp210x_dtr_rts(struct usb_serial_port *port, int on)
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@ -1770,6 +1796,7 @@ static int cp210x_port_probe(struct usb_serial_port *port)
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return -ENOMEM;
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port_priv->bInterfaceNumber = cp210x_interface_num(serial);
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mutex_init(&port_priv->mutex);
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usb_set_serial_port_data(port, port_priv);
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