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From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
To: linux-serial@vger.kernel.org
Cc: gregkh@linuxfoundation.org, jslaby@suse.com,
	michal.simek@xilinx.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, git@xilinx.com,
	Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Subject: [PATCH v2 1/2] serial: uartps: Wait for tx_empty in console setup
Date: Thu,  9 Apr 2020 11:56:02 +0530	[thread overview]
Message-ID: <1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com> (raw)
In-Reply-To: <1586413563-29125-1-git-send-email-raviteja.narayanam@xilinx.com>

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 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 6b26f76..0bf946b 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1260,6 +1260,7 @@ 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 (!port->membase) {
 		pr_debug("console on " CDNS_UART_TTY_NAME "%i not present\n",
@@ -1270,6 +1271,13 @@ 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);
 }
 #endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
-- 
2.7.4


WARNING: multiple messages have this Message-ID (diff)
From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
To: linux-serial@vger.kernel.org
Cc: Raviteja Narayanam <raviteja.narayanam@xilinx.com>,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	michal.simek@xilinx.com, git@xilinx.com, jslaby@suse.com,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/2] serial: uartps: Wait for tx_empty in console setup
Date: Thu,  9 Apr 2020 11:56:02 +0530	[thread overview]
Message-ID: <1586413563-29125-2-git-send-email-raviteja.narayanam@xilinx.com> (raw)
In-Reply-To: <1586413563-29125-1-git-send-email-raviteja.narayanam@xilinx.com>

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 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 6b26f76..0bf946b 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1260,6 +1260,7 @@ 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 (!port->membase) {
 		pr_debug("console on " CDNS_UART_TTY_NAME "%i not present\n",
@@ -1270,6 +1271,13 @@ 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);
 }
 #endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
-- 
2.7.4


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  reply	other threads:[~2020-04-09  6:27 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-09  6:26 [PATCH v2 0/2] serial: uartps: Add tx_empty checks Raviteja Narayanam
2020-04-09  6:26 ` Raviteja Narayanam
2020-04-09  6:26 ` Raviteja Narayanam [this message]
2020-04-09  6:26   ` [PATCH v2 1/2] serial: uartps: Wait for tx_empty in console setup Raviteja Narayanam
2020-04-09  6:26 ` [PATCH v2 2/2] serial: uartps: Use cdns_uart_tx_empty in console_write Raviteja Narayanam
2020-04-09  6:26   ` Raviteja Narayanam
2020-04-13 10:00 ` [PATCH v2 0/2] serial: uartps: Add tx_empty checks Shubhrajyoti Datta
2020-04-13 10:00   ` Shubhrajyoti Datta

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