Hello Hector,
> Terminate any DMA transfer and verify the TX FIFO is empty.
>
> Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
> ---
> drivers/tty/serial/mxs-auart.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/drivers/tty/serial/mxs-auart.c
> b/drivers/tty/serial/mxs-auart.c index 9f0461778fc1..d9bf6e103f65 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -782,6 +782,28 @@ static unsigned int mxs_auart_tx_empty(struct
> uart_port *u) return 0;
> }
>
> +/*
> + * Flush the transmit buffer.
> + * Locking: called with port lock held and IRQs disabled.
> + */
> +static void mxs_auart_flush_buffer(struct uart_port *u)
> +{
> + struct mxs_auart_port *s = to_auart_port(u);
> + struct dma_chan *channel = s->tx_dma_chan;
> + unsigned int to;
> +
> + if (auart_dma_enabled(s)) {
> + /* Avoid deadlock with the DMA engine callback */
> + spin_unlock(&s->port.lock);
> + dmaengine_terminate_all(channel);
> + spin_lock(&s->port.lock);
Can you not maybe just set some flag here to tell the DMA engine callback things
are shutting down and to don't do anything funny anymore ?
> + }
> + /* Wait for the FIFO to flush */
> + to = u->timeout;
> + while (!mxs_auart_tx_empty(u) && to--)
> + mdelay(1);
Maybe you can put some cond_resched() into the loop to avoid wasting too many
cycles ?
> +}
> +
> static void mxs_auart_start_tx(struct uart_port *u)
> {
> struct mxs_auart_port *s = to_auart_port(u);
> @@ -828,6 +850,7 @@ static struct uart_ops mxs_auart_ops = {
> .get_mctrl = mxs_auart_get_mctrl,
> .startup = mxs_auart_startup,
> .shutdown = mxs_auart_shutdown,
> + .flush_buffer = mxs_auart_flush_buffer,
> .set_termios = mxs_auart_settermios,
> .type = mxs_auart_type,
> .release_port = mxs_auart_release_port,
Best regards,
Marek Vasut
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