Re: [PATCH v5 2/3] tty: serial: use uart_port_tx() helper

[Jiri Slaby]

Hi,

On 21. 11. 22, 21:27, Michael Walle wrote:
> This will break serial output for the userspace on my board
> (arch/arm/boot/dts/lan966x-kontron-kswitch-d10-mmt*dts). The uart_port_tx()
> helper will call __port->ops->stop_tx(__port) if uart_circ_chars_pending()
> returns 0. But the code above, doesn't do that. In fact, removing the
> stop_tx() call in the helper macro, will fix the console output.
>
> Any ideas how to fix that?

Hm, so ATMEL_US_TXRDY is removed from tx_done_mask in stop_tx, but not 
added back in start_tx. So the tx interrupt is never handled (the tx 
tasklet is not scheduled to send the queue chars) in 
atmel_handle_transmit().

Any chance, the below fixes it?

diff --git a/drivers/tty/serial/atmel_serial.c 
b/drivers/tty/serial/atmel_serial.c
index 11bf2466390e..395370e0c77b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -596,6 +596,8 @@ static void atmel_start_tx(struct uart_port *port)
                /* re-enable PDC transmit */
                atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);

+       atmel_port->tx_done_mask |= ATMEL_US_TXRDY;
+
        /* Enable interrupts */
        atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);


thanks,
--
js