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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Raviteja Narayanam <raviteja.narayanam@xilinx.com>,
	Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <sashal@kernel.org>,
	linux-serial@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 4.9 64/90] serial: uartps: Wait for tx_empty in console setup
Date: Thu, 17 Sep 2020 22:14:29 -0400
Message-ID: <20200918021455.2067301-64-sashal@kernel.org> (raw)
In-Reply-To: <20200918021455.2067301-1-sashal@kernel.org>

From: Raviteja Narayanam <raviteja.narayanam@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@xilinx.com>
Reviewed-by: Shubhrajyoti Datta <shubhrajyoti.datta@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@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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


  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200918021455.2067301-1-sashal@kernel.org>
2020-09-18  2:14 ` [PATCH AUTOSEL 4.9 53/90] serial: 8250_port: Don't service RX FIFO if throttled Sasha Levin
2020-09-18  2:14 ` [PATCH AUTOSEL 4.9 54/90] serial: 8250_omap: Fix sleeping function called from invalid context during probe Sasha Levin
2020-09-18  2:14 ` [PATCH AUTOSEL 4.9 55/90] serial: 8250: 8250_omap: Terminate DMA before pushing data on RX timeout Sasha Levin
2020-09-18  2:14 ` Sasha Levin [this message]
2020-09-28 20:11   ` [PATCH AUTOSEL 4.9 64/90] serial: uartps: Wait for tx_empty in console setup Naresh Kamboju
2020-09-28 20:13     ` Naresh Kamboju
2020-09-29  6:59       ` Greg Kroah-Hartman
2020-09-29 17:39         ` Sasha Levin
2020-09-18  2:14 ` [PATCH AUTOSEL 4.9 73/90] tty: serial: samsung: Correct clock selection logic Sasha Levin

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