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.171283761... 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 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)