From: Mingrui Ren <jiladahe1997@xxxxxxxxx> [ Upstream commit aef1b6a27970607721a618a0b990716ca8dbbf97 ] As described in Documentation, poll_init() is called by kgdb to initialize hardware which supports both poll_put_char() and poll_get_char(). It's necessary to enable TXEN bit, otherwise, it will cause hardware fault and kernel panic when calling imx_poll_put_char(). Generally, if use /dev/ttymxc0 as kgdb console as well as system console, ttymxc0 is initialized early by system console which does enable TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only initialized by imx_poll_init() cannot enable the TXEN bit, which will cause kernel panic. Signed-off-by: Mingrui Ren <jiladahe1997@xxxxxxxxx> Link: https://lore.kernel.org/r/20201202072543.151-1-972931182@xxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/tty/serial/imx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 7a6e26b12bf64..f3626ee1b06a2 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1784,7 +1784,7 @@ static int imx_uart_poll_init(struct uart_port *port) ucr1 |= UCR1_UARTEN; ucr1 &= ~(UCR1_TXMPTYEN | UCR1_RTSDEN | UCR1_RRDYEN); - ucr2 |= UCR2_RXEN; + ucr2 |= UCR2_RXEN | UCR2_TXEN; ucr2 &= ~UCR2_ATEN; imx_uart_writel(sport, ucr1, UCR1); -- 2.27.0
