On Mon, Sep 23, 2019 at 10:24:44AM +0800, Ji-Ze Hong (Peter Hong) wrote:
> Add tx_empty() function for F81232.
>
> Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@xxxxxxxxx>
> ---
> drivers/usb/serial/f81232.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
> index c07d376c743d..b42b3738a768 100644
> --- a/drivers/usb/serial/f81232.c
> +++ b/drivers/usb/serial/f81232.c
> @@ -685,6 +685,23 @@ static void f81232_dtr_rts(struct usb_serial_port *port, int on)
> f81232_set_mctrl(port, 0, TIOCM_DTR | TIOCM_RTS);
> }
>
> +static bool f81232_tx_empty(struct usb_serial_port *port)
> +{
> + int status;
> + u8 tmp;
> +
> + status = f81232_get_register(port, LINE_STATUS_REGISTER, &tmp);
> + if (status) {
> + dev_err(&port->dev, "get LSR status failed: %d\n", status);
> + return false;
You need to return true here on errors like the other drivers do
(consider a disconnected device where you end up with -ENODEV here).
> + }
> +
> + if ((tmp & UART_LSR_TEMT) != UART_LSR_TEMT)
> + return false;
> +
> + return true;
> +}
Johan
