From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Esben Haabendal <esben@geanix.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
jirislaby@kernel.org, shawnguo@kernel.org,
u.kleine-koenig@pengutronix.de, ilpo.jarvinen@linux.intel.com,
cniedermaier@dh-electronics.com, l.sanfilippo@kunbus.com,
frank.li@vivo.com, tglx@linutronix.de, rickaran@axis.com,
linux-serial@vger.kernel.org, imx@lists.linux.dev,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH AUTOSEL 5.15 7/9] serial: imx: Introduce timeout when waiting on transmitter empty
Date: Wed, 5 Jun 2024 07:54:05 -0400 [thread overview]
Message-ID: <20240605115415.2964165-7-sashal@kernel.org> (raw)
In-Reply-To: <20240605115415.2964165-1-sashal@kernel.org>
From: Esben Haabendal <esben@geanix.com>
[ Upstream commit e533e4c62e9993e62e947ae9bbec34e4c7ae81c2 ]
By waiting at most 1 second for USR2_TXDC to be set, we avoid a potential
deadlock.
In case of the timeout, there is not much we can do, so we simply ignore
the transmitter state and optimistically try to continue.
Signed-off-by: Esben Haabendal <esben@geanix.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/919647898c337a46604edcabaf13d42d80c0915d.1712837613.git.esben@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/imx.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 0587beaaea08d..b9ef426d5aae3 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -27,6 +27,7 @@
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/io.h>
+#include <linux/iopoll.h>
#include <linux/dma-mapping.h>
#include <asm/irq.h>
@@ -2024,7 +2025,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
struct imx_port *sport = imx_uart_ports[co->index];
struct imx_port_ucrs old_ucr;
unsigned long flags;
- unsigned int ucr1;
+ unsigned int ucr1, usr2;
int locked = 1;
if (sport->port.sysrq)
@@ -2055,8 +2056,8 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
* Finally, wait for transmitter to become empty
* and restore UCR1/2/3
*/
- while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
-
+ read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,
+ 0, USEC_PER_SEC, false, sport, USR2);
imx_uart_ucrs_restore(sport, &old_ucr);
if (locked)
--
2.43.0
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parent reply other threads:[~2024-06-05 11:54 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20240605115415.2964165-1-sashal@kernel.org>]
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