This is a note to let you know that I've just added the patch titled
serial: imx: Introduce timeout when waiting on transmitter empty
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-imx-introduce-timeout-when-waiting-on-transmi.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 947102742d5ab0c72a647568ecb2487cc46067a6
Author: Esben Haabendal <esben@xxxxxxxxxx>
Date: Thu Apr 11 14:19:23 2024 +0200
serial: imx: Introduce timeout when waiting on transmitter empty
[ 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@xxxxxxxxxx>
Acked-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/919647898c337a46604edcabaf13d42d80c0915d.1712837613.git.esben@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e148132506161..09c1678ddfd49 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/io.h>
+#include <linux/iopoll.h>
#include <linux/dma-mapping.h>
#include <asm/irq.h>
@@ -2010,7 +2011,7 @@ 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)
@@ -2041,8 +2042,8 @@ 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)
