Re: [PATCH 2/2] serial: uartps: Add a timeout to the tx empty wait

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Please ignore will resend.

On Tue, May 21, 2019 at 4:13 PM Shubhrajyoti Datta
<shubhrajyoti.datta@xxxxxxxxxx> wrote:
>
> Add a timeout to the tx empty wait.
>
> Reported-by: Jean-Francois Dagenais <jeff.dagenais@xxxxxxxxx>
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxxxxx>
> ---
>  drivers/tty/serial/xilinx_uartps.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
> index 8850790..dc86511 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -26,12 +26,14 @@
>  #include <linux/of.h>
>  #include <linux/module.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/iopoll.h>
>
>  #define CDNS_UART_TTY_NAME     "ttyPS"
>  #define CDNS_UART_NAME         "xuartps"
>  #define CDNS_UART_MAJOR                0       /* use dynamic node allocation */
>  #define CDNS_UART_FIFO_SIZE    64      /* FIFO size */
>  #define CDNS_UART_REGISTER_SPACE       0x1000
> +#define TX_TIMEOUT             500000
>
>  /* Rx Trigger level */
>  static int rx_trigger_level = 56;
> @@ -688,14 +690,18 @@ static void cdns_uart_set_termios(struct uart_port *port,
>         unsigned int cval = 0;
>         unsigned int baud, minbaud, maxbaud;
>         unsigned long flags;
> -       unsigned int ctrl_reg, mode_reg;
> +       unsigned int ctrl_reg, mode_reg, val;
> +       int err;
>
>         /* Wait for the transmit FIFO to empty before making changes */
>         if (!(readl(port->membase + CDNS_UART_CR) &
>                                 CDNS_UART_CR_TX_DIS)) {
> -               while (!(readl(port->membase + CDNS_UART_SR) &
> -                               CDNS_UART_SR_TXEMPTY)) {
> -                       cpu_relax();
> +               err = readl_poll_timeout(port->membase + CDNS_UART_SR,
> +                                        val, (val & CDNS_UART_SR_TXEMPTY),
> +                                        1000, TX_TIMEOUT);
> +               if (err) {
> +                       dev_info(port->dev, "timed out waiting for tx empty");
> +                       return;
>                 }
>         }
>         spin_lock_irqsave(&port->lock, flags);
> --
> 2.1.1
>
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