| Message ID | 1586278391-9061-1-git-send-email-raviteja.narayanam@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | serial: uartps: Wait for tx_empty in console setup | expand |
Hi , On Tue, Apr 7, 2020 at 10:25 PM Raviteja Narayanam <raviteja.narayanam@xilinx.com> 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 <shubhrajyoti.datta@xilinx.com>
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 <raviteja.narayanam@xilinx.com> > --- > 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: linux-serial-owner@vger.kernel.org <linux-serial- > owner@vger.kernel.org> On Behalf Of Maarten Brock > Sent: Wednesday, April 8, 2020 9:21 PM > To: Raviteja Narayanam <rna@xilinx.com> > Cc: linux-serial@vger.kernel.org; gregkh@linuxfoundation.org; > jslaby@suse.com; Michal Simek <michals@xilinx.com>; linux-arm- > kernel@lists.infradead.org; linux-kernel@vger.kernel.org; git <git@xilinx.com>; > linux-serial-owner@vger.kernel.org > 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 <raviteja.narayanam@xilinx.com> > > --- > > 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
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 */
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@xilinx.com> --- drivers/tty/serial/xilinx_uartps.c | 10 ++++++++++ 1 file changed, 10 insertions(+)