Hi, On Wed, Jul 05, 2017 at 03:38:45PM +0200, Uwe Kleine-König wrote: > Cc += Clemens Gruber + Fabio Estevam > > On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote: > > From: Nandor Han <nandor.han@xxxxxx> > > > > CTSC and CTS are not related to DMA and might add > > disruption in some cases. > > > > Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx> > > If it was Nandor Han who created this patch, it would be great to get > his sob. If it was you, drop the From: line above. > > > --- > > drivers/tty/serial/imx.c | 5 ----- > > 1 file changed, 5 deletions(-) > > > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > > index 5291b86..dd3ebb4 100644 > > --- a/drivers/tty/serial/imx.c > > +++ b/drivers/tty/serial/imx.c > > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport) > > imx_stop_rx_dma(sport); > > imx_stop_tx_dma(sport); > > > > - /* clear UCR2 */ > > - temp = readl(sport->port.membase + UCR2); > > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN); > > - writel(temp, sport->port.membase + UCR2); > > - > > Before this patch imx_disable_dma resulted in the #CTS pin being high > (inactive). > > Does this qualify as a fix? If so, you should sort this patch to the > beginning of the series. Did you do test this patch and its effects > separately? > > @Clemens: maybe this patch makes a relevant difference when the port is > operated in rs485 mode. Do you care to test? I just finished testing it. The results are about the same as with v1 of this patch series: Applying v2 of patch 1/6, 2/6 and 3/6 (or even 3/6 alone) does not fix the RS-485 DMA bug. It behaves exactly the same as without these patches, meaning the whole xmit circ_buf (UART_XMIT_SIZE bytes) is sent out, as seen in the logic analyzer screenshots from my first bug report: https://pqgruber.com/rs485_results.png Applying the whole series does make a (small) difference though: The first few transmissions after a fresh boot work correctly! However, after a few transmissions, characters are sent out twice and longer transmissions are garbled, although not in the same way as before. The whole circ_buf is no longer sent out. With all patches from this series applied, I see the following on the logic analyzer, when calling "echo Test > /dev/ttymxc4": https://pqgruber.com/rs485txtest.png (This pattern is not always the same, sometimes it is TeTesstt\n\n, sometimes TeTesst\nt\n or TeTsestt\n\n and so on) This behavior is reproducible on i.MX6Q and i.MX6D, not on i.MX6S/etc., I therefore assume that it is a SMP-/locking-related problem. I will try to debug this further, and verify if - with this series applied - xmit->tail is still jumping over xmit->head. And when exactly this is happening. Help is much appreciated! Best regards, Clemens -- 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
