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    SubjectRe: [PATCH v5 2/3] tty: serial: use uart_port_tx() helper
    Hi,

    Am 2022-11-22 08:02, schrieb Jiri Slaby:
    > 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,

    Unfortunately, that doesn't help. Btw, some characters are transmitted:


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    -michael

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