On Fri, 24 Mar 2023, Francesco Dolcini wrote: > Hello > > On Fri, Mar 24, 2023 at 01:47:59PM +0200, Ilpo Järvinen wrote: > > On Fri, 24 Mar 2023, Stefan Wahren wrote: > > > after switching to Linux 6.1.21 on our Tarragon board (i.MX6ULL SoC), we > > > experience the following issues with the debug UART (115200 baud, 8N1, no > > > hardware flow control): > > > > > > - overrun errors if we paste in multiple text lines while system is idle > > > - no reaction to single key strokes while system is on higher load > > > > > > After reverting 7a637784d517 ("serial: imx: reduce RX interrupt frequency") > > > the issue disappear. > > > > > > Maybe it's worth to mention that the Tarragon board uses two additional > > > application UARTs with similiar baud rates (9600 - 115200 baud, no hardware > > > flow control) for RS485 communication, but there are no overrun errors (with > > > and without the mention change). > > > > This has come up earlier, see e.g.: > > > > https://lore.kernel.org/linux-serial/20221003110850.GA28338@xxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > yep, it looks exactly the same issue. > > We did not verify if this was affecting other UARTs. However, isn't RS485 > half-duplex? While half-duplex is more likely by far due simplicity, RS485 could also be full-duplex. It seems imx driver supports for both modes. -- i. > This is very likely a difference compared to the RS232 > console port. > > I am also not really convinced this is a proper regression, while 7a637784d517 > clearly is making the situation _worst_, we had some issues even before - > unfortunately I have no much more details available.