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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	kernel@pengutronix.de,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Valentin Caron <valentin.caron@foss.st.com>,
	Lino Sanfilippo <l.sanfilippo@kunbus.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Erwan Le Ray <erwan.leray@foss.st.com>,
	Peter Hurley <peter@hurleysoftware.com>,
	Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
	linux-serial@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org
Subject: [PATCH 2/2] serial: stm32: Reset .throttled state in .startup()
Date: Wed, 17 Apr 2024 11:03:28 +0200	[thread overview]
Message-ID: <a784f80d3414f7db723b2ec66efc56e1ad666cbf.1713344161.git.u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <cover.1713344161.git.u.kleine-koenig@pengutronix.de>

When an UART is opened that still has .throttled set from a previous
open, the RX interrupt is enabled but the irq handler doesn't consider
it. This easily results in a stuck irq with the effect to occupy the CPU
in a tight loop.

So reset the throttle state in .startup() to ensure that RX irqs are
handled.

Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/stm32-usart.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 2bea1d7c9858..e1e7bc04c579 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1080,6 +1080,7 @@ static int stm32_usart_startup(struct uart_port *port)
 		val |= USART_CR2_SWAP;
 		writel_relaxed(val, port->membase + ofs->cr2);
 	}
+	stm32_port->throttled = false;
 
 	/* RX FIFO Flush */
 	if (ofs->rqr != UNDEF_REG)
-- 
2.43.0


WARNING: multiple messages have this Message-ID (diff)
From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	kernel@pengutronix.de,
	Alexandre Torgue <alexandre.torgue@foss.st.com>,
	Valentin Caron <valentin.caron@foss.st.com>,
	Lino Sanfilippo <l.sanfilippo@kunbus.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Erwan Le Ray <erwan.leray@foss.st.com>,
	Peter Hurley <peter@hurleysoftware.com>,
	Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
	linux-serial@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org
Subject: [PATCH 2/2] serial: stm32: Reset .throttled state in .startup()
Date: Wed, 17 Apr 2024 11:03:28 +0200	[thread overview]
Message-ID: <a784f80d3414f7db723b2ec66efc56e1ad666cbf.1713344161.git.u.kleine-koenig@pengutronix.de> (raw)
In-Reply-To: <cover.1713344161.git.u.kleine-koenig@pengutronix.de>

When an UART is opened that still has .throttled set from a previous
open, the RX interrupt is enabled but the irq handler doesn't consider
it. This easily results in a stuck irq with the effect to occupy the CPU
in a tight loop.

So reset the throttle state in .startup() to ensure that RX irqs are
handled.

Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/tty/serial/stm32-usart.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 2bea1d7c9858..e1e7bc04c579 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -1080,6 +1080,7 @@ static int stm32_usart_startup(struct uart_port *port)
 		val |= USART_CR2_SWAP;
 		writel_relaxed(val, port->membase + ofs->cr2);
 	}
+	stm32_port->throttled = false;
 
 	/* RX FIFO Flush */
 	if (ofs->rqr != UNDEF_REG)
-- 
2.43.0


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

  parent reply	other threads:[~2024-04-17  9:04 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-17  9:03 [PATCH 0/2] serial: stm32: Two fixes Uwe Kleine-König
2024-04-17  9:03 ` Uwe Kleine-König
2024-04-17  9:03 ` [PATCH 1/2] serial: stm32: Return IRQ_NONE in the ISR if no handling happend Uwe Kleine-König
2024-04-17  9:03   ` Uwe Kleine-König
2024-04-17  9:03 ` Uwe Kleine-König [this message]
2024-04-17  9:03   ` [PATCH 2/2] serial: stm32: Reset .throttled state in .startup() Uwe Kleine-König

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