Hello Hector,
On Wed, Oct 02, 2013 at 02:02:44PM +0200, Hector Palacios wrote:
> The shutdown function was not waiting for the FIFO (which may be the
> real 16 byte FIFO or the DMA buffer, if DMA is enabled) to flush
> before disabling the AUART.
> This lead to many bytes not being transferred (specially at low
> baudrates), as they were still in the DMA buffer when the AUART was
> shutdown.
> This patch also adds the check for the BUSY flag before disabling
> the AUART.
>
> Signed-off-by: Hector Palacios <hector.palacios@xxxxxxxx>
> ---
> drivers/tty/serial/mxs-auart.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 9f046177..589b595 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -757,9 +757,22 @@ static int mxs_auart_startup(struct uart_port *u)
> return 0;
> }
>
> +static unsigned int mxs_auart_tx_empty(struct uart_port *u);
> +
> static void mxs_auart_shutdown(struct uart_port *u)
> {
> struct mxs_auart_port *s = to_auart_port(u);
> + unsigned int to;
> +
> + /* Wait for the FIFO to flush */
> + to = u->timeout;
> + while (!mxs_auart_tx_empty(u) && to--)
> + mdelay(1);
> +
> + /* Wait for UART to become idle ... */
> + to = u->timeout;
> + while ((readl(u->membase + AUART_STAT) & AUART_STAT_BUSY) && to--)
> + mdelay(1);
If the 2nd loop is needed the tx_empty callback is buggy. According to
Documentation/serial/driver tx_empty "tests whether the transmitter fifo
and shifter for the port [...] is empty". I guess it only tests for the
fifo part? Time for another fix ...
Best regards
Uwe
> if (auart_dma_enabled(s))
> mxs_auart_dma_exit(s);
> --
> 1.8.4
>
>
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
