Re: [PATCH AUTOSEL 4.4 42/64] serial: uartps: Wait for tx_empty in console setup
From: Naresh Kamboju <hidden>
Date: 2020-09-28 20:17:18
Also in:
linux-serial, lkml, stable
On Fri, 18 Sep 2020 at 07:51, Sasha Levin [off-list ref] wrote:
From: Raviteja Narayanam <redacted> [ 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 <redacted> Reviewed-by: Shubhrajyoti Datta <redacted> Link: https://lore.kernel.org/r/1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com (local) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
stable rc branch 4.4 arm64 build broken.
../drivers/tty/serial/xilinx_uartps.c: In function ‘cdns_uart_console_setup’:
../drivers/tty/serial/xilinx_uartps.c:1170:40: error: ‘TX_TIMEOUT’
undeclared (first use in this function)
1170 | time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT);
^~~~~~~~~~
Reported-by: Naresh Kamboju <redacted>
quoted hunk ↗ jump to hunk
--- 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 06efcef1b4953..5b4469098888a 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c@@ -1152,6 +1152,7 @@ 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;@@ -1165,6 +1166,13 @@ 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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