[PATCH AUTOSEL 4.9 64/90] serial: uartps: Wait for tx_empty in console setup

[Naresh Kamboju]

On Fri, 18 Sep 2020 at 07:55, Sasha Levin <sashal at kernel.org> wrote:
>
> From: Raviteja Narayanam <raviteja.narayanam at xilinx.com>
>
> [ Upstream commit 42e11948ddf68b9f799cad8c0ddeab0a39da33e8 ]
>
> On some platforms, the log is corrupted while console is being
> registered. It is observed that when set_termios is called, there
> are still some bytes in the FIFO to be transmitted.
>
> So, wait for tx_empty inside cdns_uart_console_setup before calling
> set_termios.
>
> Signed-off-by: Raviteja Narayanam <raviteja.narayanam at xilinx.com>
> Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta at xilinx.com>
> Link: https://lore.kernel.org/r/1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Signed-off-by: Sasha Levin <sashal at kernel.org>

stable rc 4.9 arm64 build broken.

drivers/tty/serial/xilinx_uartps.c: In function 'cdns_uart_console_setup':
drivers/tty/serial/xilinx_uartps.c:1286:40: error: 'TX_TIMEOUT'
undeclared (first use in this function); did you mean 'ETIMEDOUT'?
  time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
                                        ^~~~~~~~~~
                                        ETIMEDOUT
drivers/tty/serial/xilinx_uartps.c:1286:40: note: each undeclared
identifier is reported only once for each function it appears in
  CC      drivers/usb/core/port.o
scripts/Makefile.build:304: recipe for target
'drivers/tty/serial/xilinx_uartps.o' failed
make[5]: *** [drivers/tty/serial/xilinx_uartps.o] Error 1

Reported-by: Naresh Kamboju <naresh.kamboju at linaro.org>

full test log link,
https://ci.linaro.org/view/lkft/job/openembedded-lkft-linux-stable-rc-4.9/DISTRO=lkft,MACHINE=hikey,label=docker-lkft/996/consoleText


> ---
>  drivers/tty/serial/xilinx_uartps.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
> index eb61a07fcbbc3..07ea71a611678 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -1268,6 +1268,7 @@ static int cdns_uart_console_setup(struct console *co, char *options)
>         int bits = 8;
>         int parity = 'n';
>         int flow = 'n';
> +       unsigned long time_out;
>
>         if (co->index < 0 || co->index >= CDNS_UART_NR_PORTS)
>                 return -EINVAL;
> @@ -1281,6 +1282,13 @@ static int cdns_uart_console_setup(struct console *co, char *options)
>         if (options)
>                 uart_parse_options(options, &baud, &parity, &bits, &flow);
>
> +       /* Wait for tx_empty before setting up the console */
> +       time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
> +
> +       while (time_before(jiffies, time_out) &&
> +              cdns_uart_tx_empty(port) != TIOCSER_TEMT)
> +               cpu_relax();
> +
>         return uart_set_options(port, co, baud, parity, bits, flow);
>  }
>
> --
> 2.25.1
>


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