[RFC PATCH] tty/serial: atmel: fix TX path in atmel_console_write()
From: Richard Genoud <hidden>
Date: 2017-03-15 16:20:53
Also in:
linux-serial, lkml, stable
On 15/03/2017 16:29, Nicolas Ferre wrote:
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@microchip.com>
Fixes: 89d8232411a8 ("tty/serial: atmel_serial: BUG: stop DMA from transmitting
in stop_tx")
Cc: stable <redacted> # 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,So, I'm guessing that you may see some lines/characters printed twice on the screen, don't you ?
quoted hunk ↗ jump to hunk
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); /*
Richard.