Hi Fabio, On Sun, Jan 08, 2017 at 12:30:24AM -0200, Fabio Estevam wrote: > Hi Clemens, > > On Sat, Jan 7, 2017 at 9:06 PM, Clemens Gruber > <clemens.gruber@xxxxxxxxxxxx> wrote: > > > Just remuxed GPIO signals to these pads, applied your two patches and > > used rts-gpios in the DT but I still see the same problem :/ > > > > When transmit something, I get doubled characters, then zeros and at the > > end garbled data of previous transmissions, same as described in my > > first post (Logic analyzer: https://pqgruber.com/rs485_results.png) > > The data is always 4096 bytes long, this explains why the echo command > > is blocking for about 4 seconds (<- 4096 bytes at a baudrate of 9600). > > The TE line is also high until all 4096 bytes are sent. > > > > I think this comes from the UART_XMIT_SIZE which is defined to the page > > size. > > Maybe there is something wrong in imx_transmit_buffer and leads to the > > whole circular buffer being sent out all the time, not stopping.. > > > > Do these debug logs tell you anything? > > https://gist.github.com/clemensg/1ac5ee8a8ea32acc9145c5aa8407aea5 > > > > I am analyzing the signals coming directly from the i.MX6Q, so this must > > be a software problem, but I don't understand why it works for you, if > > we use the same software. > > > > Do you use any other patches on top of mainline and do you use the SDMA > > scripts from the ROM? > > No, I use the original 4.9 + the two patches I sent. Yes, I do use the > SDMA scripts from ROM. > > Here is the procedure I did to try to reproduce the issue you reported: > > (The rs485conf is available at: > https://github.com/mniestroj/rs485conf/blob/master/main.c ) > > First of all I enable rs485 for ttymxc3 using the rs485conf application: > > root@imx6qsabresd:/home# ./rs485conf /dev/ttymxc3 -e 1 > [ 27.106517] random: crng init done > = Current configuration: > RS485 enabled: false > RTS on send: high > RTS after send: low > RTS delay before send: 0 > RTS delay after send: 0 > Receive during sending data: true > > = New configuration: > RS485 enabled: true > RTS on send: high > RTS after send: low > RTS delay before send: 0 > RTS delay after send: 0 > Receive during sending data: true > > = Saved configuration: > RS485 enabled: true > RTS on send: high > RTS after send: low > RTS delay before send: 0 > RTS delay after send: 0 > Receive during sending data: true > root@imx6qsabresd:/ho > > Then > > root@imx6qsabresd:/home# echo A > /dev/ttymxc3 > > (wait 10 seconds) > > root@imx6qsabresd:/home# echo B > /dev/ttymxc3 > > (wait 10 seconds) > > root@imx6qsabresd:/home# echo C > /dev/ttymxc3 > > On the serial console at 9600bps only the: > A > B > C > > are seen, so not duplicated characters, nor noise is seen on the console. I just did the experiment with your configuration and the rs485conf tool you mentioned. But still, no luck :( What's the revision of the i.MX6Q on your board? Mine is 1.5 (TO 1.3) Another example: If I run the following on the board.. while true; do echo ABCDEFGHIJKLM > /dev/ttymxc4 sleep 0.5 echo abc > /dev/ttymxc4 > /dev/ttymxc4 sleep 0.5 done Many transmits contain garbled (doubled and sometimes also extended to a length of 4096 bytes, containing zeros) data. I can see a few transmissions that are sent correctly, though. Interesting side note: With the following patch, the problems disappear: diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 451e50f6d77a..eb9f0ce6c34a 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1270,8 +1270,10 @@ static int imx_startup(struct uart_port *port) writel(temp & ~UCR4_DREN, sport->port.membase + UCR4); /* Can we enable the DMA support? */ +#if 0 if (!uart_console(port) && !sport->dma_is_inited) imx_uart_dma_init(sport); +#endif spin_lock_irqsave(&sport->port.lock, flags); /* Reset fifo's and state machines */ -- 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
