On Mon, Jan 02, 2017 at 03:16:46PM +0100, Richard Genoud wrote: > 2017-01-02 12:13 GMT+01:00 Nicolas Ferre <nicolas.ferre@xxxxxxxxx>: > > Le 13/12/2016 à 17:27, Richard Genoud a écrit : > >> If we don't disable the transmitter in atmel_stop_tx, the DMA buffer > >> continues to send data until it is emptied. > >> This cause problems with the flow control (CTS is asserted and data are > >> still sent). > >> > >> So, disabling the transmitter in atmel_stop_tx is a sane thing to do. > >> > >> Tested on at91sam9g35-cm(DMA) > >> Tested for regressions on sama5d2-xplained(Fifo) and at91sam9g20ek(PDC) > >> > >> Cc: <stable@xxxxxxxxxxxxxxx> (beware, this won't apply before 4.3) > >> Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxx> > > > > Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> > > > >> --- > >> drivers/tty/serial/atmel_serial.c | 11 +++++++++++ > >> 1 file changed, 11 insertions(+) > >> > >> NB: this is not for the 4.10 merge window, I'm just sending it now to > >> have some comments if someone is againts it. > >> > >> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > >> index 168b10cad47b..f9d42de5ab2d 100644 > >> --- a/drivers/tty/serial/atmel_serial.c > >> +++ b/drivers/tty/serial/atmel_serial.c > >> @@ -481,6 +481,14 @@ static void atmel_stop_tx(struct uart_port *port) > >> /* disable PDC transmit */ > >> atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS); > >> } > >> + > >> + /* > >> + * Disable the transmitter. > >> + * This is mandatory when DMA is used, otherwise the DMA buffer > >> + * is fully transmitted. > >> + */ > >> + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS); > >> + > >> /* Disable interrupts */ > >> atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask); > >> > >> @@ -513,6 +521,9 @@ static void atmel_start_tx(struct uart_port *port) > >> > >> /* Enable interrupts */ > >> atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask); > >> + > >> + /* re-enable the transmitter */ > >> + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN); > >> } > >> > >> /* > >> > > > > > > -- > > Nicolas Ferre > > Greg, could you also take this patch in your tree ? Yup! -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html