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From: Erwan Le Ray <erwan.leray@foss.st.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: <linux-serial@vger.kernel.org>,
	<linux-stm32@st-md-mailman.stormreply.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	Erwan Le Ray <erwan.leray@foss.st.com>,
	Fabrice Gasnier <fabrice.gasnier@foss.st.com>,
	Valentin Caron <valentin.caron@foss.st.com>
Subject: [PATCH v2 03/13] serial: stm32: fix incorrect characters on console
Date: Thu, 4 Mar 2021 17:22:58 +0100	[thread overview]
Message-ID: <20210304162308.8984-4-erwan.leray@foss.st.com> (raw)
In-Reply-To: <20210304162308.8984-1-erwan.leray@foss.st.com>

Incorrect characters are observed on console during boot. This issue occurs
when init/main.c is modifying termios settings to open /dev/console on the
rootfs.

This patch adds a waiting loop in set_termios to wait for TX shift register
empty (and TX FIFO if any) before stopping serial port.

Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index c6ca8f964c69..eae54b8cf5e2 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -738,8 +738,9 @@ static void stm32_usart_set_termios(struct uart_port *port,
 	unsigned int baud, bits;
 	u32 usartdiv, mantissa, fraction, oversampling;
 	tcflag_t cflag = termios->c_cflag;
-	u32 cr1, cr2, cr3;
+	u32 cr1, cr2, cr3, isr;
 	unsigned long flags;
+	int ret;
 
 	if (!stm32_port->hw_flow_control)
 		cflag &= ~CRTSCTS;
@@ -748,6 +749,15 @@ static void stm32_usart_set_termios(struct uart_port *port,
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						isr,
+						(isr & USART_SR_TC),
+						10, 100000);
+
+	/* Send the TC error message only when ISR_TC is not set. */
+	if (ret)
+		dev_err(port->dev, "Transmission is not complete\n");
+
 	/* Stop serial port and reset value */
 	writel_relaxed(0, port->membase + ofs->cr1);
 
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: Erwan Le Ray <erwan.leray@foss.st.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: <linux-serial@vger.kernel.org>,
	<linux-stm32@st-md-mailman.stormreply.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	Erwan Le Ray <erwan.leray@foss.st.com>,
	Fabrice Gasnier <fabrice.gasnier@foss.st.com>,
	Valentin Caron <valentin.caron@foss.st.com>
Subject: [PATCH v2 03/13] serial: stm32: fix incorrect characters on console
Date: Thu, 4 Mar 2021 17:22:58 +0100	[thread overview]
Message-ID: <20210304162308.8984-4-erwan.leray@foss.st.com> (raw)
In-Reply-To: <20210304162308.8984-1-erwan.leray@foss.st.com>

Incorrect characters are observed on console during boot. This issue occurs
when init/main.c is modifying termios settings to open /dev/console on the
rootfs.

This patch adds a waiting loop in set_termios to wait for TX shift register
empty (and TX FIFO if any) before stopping serial port.

Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index c6ca8f964c69..eae54b8cf5e2 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -738,8 +738,9 @@ static void stm32_usart_set_termios(struct uart_port *port,
 	unsigned int baud, bits;
 	u32 usartdiv, mantissa, fraction, oversampling;
 	tcflag_t cflag = termios->c_cflag;
-	u32 cr1, cr2, cr3;
+	u32 cr1, cr2, cr3, isr;
 	unsigned long flags;
+	int ret;
 
 	if (!stm32_port->hw_flow_control)
 		cflag &= ~CRTSCTS;
@@ -748,6 +749,15 @@ static void stm32_usart_set_termios(struct uart_port *port,
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	ret = readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
+						isr,
+						(isr & USART_SR_TC),
+						10, 100000);
+
+	/* Send the TC error message only when ISR_TC is not set. */
+	if (ret)
+		dev_err(port->dev, "Transmission is not complete\n");
+
 	/* Stop serial port and reset value */
 	writel_relaxed(0, port->membase + ofs->cr1);
 
-- 
2.17.1


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-03-04 16:25 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-04 16:22 [PATCH v2 00/13] stm32 usart various fixes Erwan Le Ray
2021-03-04 16:22 ` Erwan Le Ray
2021-03-04 16:22 ` [PATCH v2 01/13] serial: stm32: fix probe and remove order for dma Erwan Le Ray
2021-03-04 16:22   ` Erwan Le Ray
2021-03-04 16:22 ` [PATCH v2 02/13] serial: stm32: fix startup by enabling usart for reception Erwan Le Ray
2021-03-04 16:22   ` Erwan Le Ray
2021-03-04 16:22 ` Erwan Le Ray [this message]
2021-03-04 16:22   ` [PATCH v2 03/13] serial: stm32: fix incorrect characters on console Erwan Le Ray
2021-03-04 16:22 ` [PATCH v2 04/13] serial: stm32: fix TX and RX FIFO thresholds Erwan Le Ray
2021-03-04 16:22   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 05/13] serial: stm32: fix a deadlock condition with wakeup event Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 06/13] serial: stm32: fix wake-up flag handling Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 07/13] serial: stm32: fix a deadlock in set_termios Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 08/13] serial: stm32: fix tx dma completion, release channel Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 09/13] serial: stm32: call stm32_transmit_chars locked Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 10/13] serial: stm32: fix FIFO flush in startup and set_termios Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 11/13] serial: stm32: add FIFO flush when port is closed Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 12/13] serial: stm32: fix tx_empty condition Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray
2021-03-04 16:23 ` [PATCH v2 13/13] serial: stm32: add support for "flush_buffer" ops Erwan Le Ray
2021-03-04 16:23   ` Erwan Le Ray

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