Hi Fabio, Hi Romain, On Fri, Jun 30, 2017 at 09:15:31AM -0300, Fabio Estevam wrote: > Hi Clemens, > > On Wed, Jun 21, 2017 at 11:12 AM, Fabio Estevam <festevam@xxxxxxxxx> wrote: > > >> I'd also prefer fixing the underlying problem. > > > > Yes, that would be much better. > > Just saw Romain's patch series that addresses several imx uart DMA issues: > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/516845.html > > If you have a chance, please give it a try to see if it helps on the > RS485 DMA case. Thanks, I just finished my first tests with Romain's patch series: It looks like these patches fixed some of the bugs, causing this behavior, but not all: The behavior changed, the rest of the circular buffer is no longer sent out as seen in the previous bug report (https://pqgruber.com/rs485_results.png) But now, with the patch series applied, if I transmit "Test", the logic analyzer records the following: https://pqgruber.com/rs485txtest.png Most of the time it looked like this (T e T e s s t t LF LF), but in a few cases I observed another pattern (T e T s e s t t LF LF) when transmitting "Test" by calling echo Test > /dev/ttymxc4. If I do a echo A > /dev/ttymxc4 as in my first bug report, now I always see the pattern A LF A LF on the TX line, but no longer A LF A LF 0 0 .. Interestingly, the bug does not appear the first time I try echo A after a reboot. Romain: What board did you use to test your patch series? The RS485 bug, I reported, only appears on i.MX6D and i.MX6Q, but not on single-core / non-SMP systems. Would be great if you could reproduce it! 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
