Hello,
I am unable to communicate in RS485 since I upgrade to the latest kernel
version (v4.9-rc7). Previously I was in 3.12.
It seems to be caused by commit "0058f0871efe7b01c6f2b3046c68196ab73e96da
tty/serial: atmel: fix RS485 half duplex with DMA".
RX is disabled during TX, but in my case it is not re-enabled after.
If I revert this patch, everything seems to work again.
Currently enable RX is done in atmel_tx_dma but it is not called if there are
still data to transfer... problem in that it is never done later.
So I think we should also enable RX in atmel_complete_tx_dma.
I have made this fix, and it seems to work now:
diff --git a/drivers/tty/serial/atmel_serial.c
b/drivers/tty/serial/atmel_serial.c
index 74e97dc..4190012 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -806,6 +806,10 @@ static void atmel_complete_tx_dma(void *arg)
*/
if (!uart_circ_empty(xmit))
atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
+ else if (port->rs485.flags & SER_RS485_ENABLED) {
+ /* DMA done, start RX for RS485 */
+ atmel_start_rx(port);
+ }
spin_unlock_irqrestore(&port->lock, flags);
Is it correct? or maybe there is a better way to fix it?
Thanks,
Gil
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