Messages in this thread | | | Date | Sat, 12 Aug 2017 21:54:51 +0200 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] serial: imx: Improve PIO prevention if TX DMA has been started |
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On Sat, Aug 12, 2017 at 05:12:10PM +0200, Clemens Gruber wrote: > The imx_transmit_buffer function should return if TX DMA has already > been started and not just skip over the buffer PIO write loop. (Which > did fix the initial problem, but could have unintentional side-effects) > > Tested on an i.MX6Q board with half-duplex RS-485 and with RS-232. > > Cc: Ian Jamison <ian.dev@arkver.com> > Cc: Uwe-Kleine König <u.kleine-koenig@pengutronix.de> > Fixes: 514ab34dbad6 ("serial: imx: Prevent TX buffer PIO write when a > DMA has been started")
AFAIK no newline in the Fixes: line.
> Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com> > --- > drivers/tty/serial/imx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > index 80934e7bd67f..fce538eb8c77 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -452,13 +452,14 @@ static inline void imx_transmit_buffer(struct imx_port *sport) > if (sport->dma_is_txing) { > temp |= UCR1_TDMAEN; > writel(temp, sport->port.membase + UCR1); > + return; > } else { > writel(temp, sport->port.membase + UCR1); > imx_dma_tx(sport); > }
Shouldn't the return go here?
Did you understand the problem? Can you say why this only hurts in RS485 half-duplex but not (as it seems) in regular rs232 mode?
> } > > - while (!uart_circ_empty(xmit) && !sport->dma_is_txing && > + while (!uart_circ_empty(xmit) && > !(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) { > /* send xmit->buf[xmit->tail] > * out the port here */
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
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