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 <[email protected]>
---
drivers/tty/serial/xilinx_uartps.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 6b26f76..23468ff 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1260,6 +1260,8 @@ static int cdns_uart_console_setup(struct console *co, char *options)
int bits = 8;
int parity = 'n';
int flow = 'n';
+ unsigned long time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
+ int status;
if (!port->membase) {
pr_debug("console on " CDNS_UART_TTY_NAME "%i not present\n",
@@ -1270,6 +1272,14 @@ 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 */
+ while (time_before(jiffies, time_out)) {
+ status = cdns_uart_tx_empty(port);
+ if (status == TIOCSER_TEMT)
+ break;
+ cpu_relax();
+ }
+
return uart_set_options(port, co, baud, parity, bits, flow);
}
#endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
--
2.7.4
Hi ,
On Tue, Apr 7, 2020 at 10:25 PM Raviteja Narayanam
<[email protected]> wrote:
>
> 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.
>
Reviewed-by: Shubhrajyoti Datta <[email protected]>
On 2020-04-07 18:53, Raviteja Narayanam wrote:
> 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 <[email protected]>
> ---
> drivers/tty/serial/xilinx_uartps.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/tty/serial/xilinx_uartps.c
> b/drivers/tty/serial/xilinx_uartps.c
> index 6b26f76..23468ff 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -1260,6 +1260,8 @@ static int cdns_uart_console_setup(struct
> console *co, char *options)
> int bits = 8;
> int parity = 'n';
> int flow = 'n';
> + unsigned long time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
> + int status;
>
> if (!port->membase) {
> pr_debug("console on " CDNS_UART_TTY_NAME "%i not present\n",
> @@ -1270,6 +1272,14 @@ 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 */
> + while (time_before(jiffies, time_out)) {
> + status = cdns_uart_tx_empty(port);
> + if (status == TIOCSER_TEMT)
> + break;
> + cpu_relax();
> + }
> +
> return uart_set_options(port, co, baud, parity, bits, flow);
> }
> #endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
You could do without the status variable. You could even combine the
while and if conditions.
And while you're at it, you might as well also rewrite the lines
1236-1238 to also use cdns_uart_tx_empty() for clarity.
Maarten
Hi Maarten,
Thanks for the review.
> -----Original Message-----
> From: [email protected] <linux-serial-
> [email protected]> On Behalf Of Maarten Brock
> Sent: Wednesday, April 8, 2020 9:21 PM
> To: Raviteja Narayanam <[email protected]>
> Cc: [email protected]; [email protected];
> [email protected]; Michal Simek <[email protected]>; linux-arm-
> [email protected]; [email protected]; git <[email protected]>;
> [email protected]
> Subject: Re: [PATCH] serial: uartps: Wait for tx_empty in console setup
>
> On 2020-04-07 18:53, Raviteja Narayanam wrote:
> > 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 <[email protected]>
> > ---
> > drivers/tty/serial/xilinx_uartps.c | 10 ++++++++++
> > 1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/tty/serial/xilinx_uartps.c
> > b/drivers/tty/serial/xilinx_uartps.c
> > index 6b26f76..23468ff 100644
> > --- a/drivers/tty/serial/xilinx_uartps.c
> > +++ b/drivers/tty/serial/xilinx_uartps.c
> > @@ -1260,6 +1260,8 @@ static int cdns_uart_console_setup(struct
> > console *co, char *options)
> > int bits = 8;
> > int parity = 'n';
> > int flow = 'n';
> > + unsigned long time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
> > + int status;
> >
> > if (!port->membase) {
> > pr_debug("console on " CDNS_UART_TTY_NAME "%i not
> present\n", @@
> > -1270,6 +1272,14 @@ 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 */
> > + while (time_before(jiffies, time_out)) {
> > + status = cdns_uart_tx_empty(port);
> > + if (status == TIOCSER_TEMT)
> > + break;
> > + cpu_relax();
> > + }
> > +
> > return uart_set_options(port, co, baud, parity, bits, flow); }
> > #endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
>
> You could do without the status variable. You could even combine the while
> and if conditions.
>
> And while you're at it, you might as well also rewrite the lines
> 1236-1238 to also use cdns_uart_tx_empty() for clarity.
Will send v2, addressing these.
>
> Maarten
Regards,
Raviteja N