On Fri, Dec 09, 2016 at 01:39:34PM +0800, Ji-Ze Hong (Peter Hong) wrote:
> Implement Fintek f81534 break on/off with LCR register
> It's the same with 16550A LCR register layout
>
> We'll add a shadow LCR variable to save the final LCR we
> had set due to the "read ep0" operations maybe slow down all
> the serial ports performance.
>
> Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@xxxxxxxxx>
> ---
> drivers/usb/serial/f81534.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
> index 8282a6a..1b6ba81 100644
> --- a/drivers/usb/serial/f81534.c
> +++ b/drivers/usb/serial/f81534.c
> @@ -126,8 +126,10 @@ struct f81534_serial_private {
>
> struct f81534_port_private {
> struct mutex mcr_mutex;
> + struct mutex lcr_mutex;
Using a single mutex is preferred.
> unsigned long tx_empty;
> spinlock_t msr_lock;
> + u8 shadow_lcr;
> u8 shadow_mcr;
> u8 shadow_msr;
> u8 phy_num;
> @@ -683,6 +685,7 @@ static void f81534_set_termios(struct tty_struct *tty,
> struct usb_serial_port *port,
> struct ktermios *old_termios)
> {
> + struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
> u8 new_lcr = 0;
> int status;
> u32 baud;
> @@ -721,6 +724,10 @@ static void f81534_set_termios(struct tty_struct *tty,
> break;
> }
>
> + mutex_lock(&port_priv->lcr_mutex);
> + port_priv->shadow_lcr = new_lcr;
> + mutex_unlock(&port_priv->lcr_mutex);
And this is not sufficient to prevent races with break_ctl. Hold the
mutex while updating LCR in set_port_config at least (and honour the
break state).
> +
> baud = tty_get_baud_rate(tty);
> if (!baud)
> return;
> @@ -812,6 +819,35 @@ static int f81534_read_msr(struct usb_serial_port *port)
> return 0;
> }
>
> +static void f81534_set_break(struct usb_serial_port *port, bool enable)
> +{
> + struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
> + int status;
> +
> + mutex_lock(&port_priv->lcr_mutex);
> +
> + if (enable)
> + port_priv->shadow_lcr |= UART_LCR_SBC;
> + else
> + port_priv->shadow_lcr &= ~UART_LCR_SBC;
> +
> + status = f81534_set_port_register(port, F81534_LINE_CONTROL_REG,
> + port_priv->shadow_lcr);
> + if (status) {
> + dev_err(&port->dev, "%s: set break failed: %x\n", __func__,
> + status);
%d, __func__ not needed.
> + }
> +
> + mutex_unlock(&port_priv->lcr_mutex);
> +}
> +
> +static void f81534_break_ctl(struct tty_struct *tty, int break_state)
> +{
> + struct usb_serial_port *port = tty->driver_data;
> +
> + f81534_set_break(port, break_state);
> +}
> +
> static int f81534_open(struct tty_struct *tty, struct usb_serial_port *port)
> {
> struct f81534_serial_private *serial_priv =
> @@ -877,6 +913,8 @@ static void f81534_close(struct usb_serial_port *port)
> }
>
> mutex_unlock(&serial_priv->urb_mutex);
> +
> + f81534_set_break(port, false);
Drop this too, and fold set_break into break_ctl above.
> }
>
> static int f81534_get_serial_info(struct usb_serial_port *port,
> @@ -1244,6 +1282,7 @@ static int f81534_port_probe(struct usb_serial_port *port)
>
> spin_lock_init(&port_priv->msr_lock);
> mutex_init(&port_priv->mcr_mutex);
> + mutex_init(&port_priv->lcr_mutex);
>
> /* Assign logic-to-phy mapping */
> port_priv->phy_num = f81534_logic_to_phy_port(port->serial, port);
> @@ -1389,6 +1428,7 @@ static int f81534_resume(struct usb_serial *serial)
> .dtr_rts = f81534_dtr_rts,
> .process_read_urb = f81534_process_read_urb,
> .ioctl = f81534_ioctl,
> + .break_ctl = f81534_break_ctl,
> .tiocmget = f81534_tiocmget,
> .tiocmset = f81534_tiocmset,
> .write_bulk_callback = f81534_write_usb_callback,
Thanks,
Johan
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