A side effect of 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA
from transmitting in stop_tx") is that the console can be called with
TX path disabled. Then the system would hang trying to push charecters
out in atmel_console_putchar().
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting
in stop_tx")
Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.4+
---
Hi Richard,
I found this to fix the problem with system hang in my linux-4.4-at91 branch
(in the atmel_console_putchar() waiting loop actually). I'm open to more
insignt.
As we cannot figure out if this bit is set or not, I didn't preserve the
current status...
Regards,
drivers/tty/serial/atmel_serial.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index dcebb28ffbc4..7372dbdb7a4c 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2483,6 +2483,9 @@ static void atmel_console_write(struct console *co, const char *s, u_int count)
pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN;
atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
+ /* Make sure that tx path is actually able to send characters */
+ atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN);
+
uart_console_write(port, s, count, atmel_console_putchar);
/*
--
2.9.0