On Tue, May 21, 2019 at 04:33:38PM +0530, shubhrajyoti.datta@xxxxxxxxx wrote:
> From: Shubhrajyoti Datta <shubhrajyoti.datta@xxxxxxxxxx>
>
> In case the cable is not connected then the target gets into
> a infinite wait for tx empty.
> 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");
That is not an "informational" message, isn't it an error? And if this
happens, what can userspace do about it? Why report it at all?
thanks,
greg k-h
