[PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx

Sebastian Andrzej Siewior bigeasy at linutronix.de
Mon Sep 29 09:15:05 PDT 2014

* Peter Hurley | 2014-09-17 08:20:41 [-0400]:

>> So I connected my am335x-evm
>> with beagle board xm because both of them have an old fashion UART
>> connector (instead those uart-to-usb). Both configured with HW-Flow and
>> I haven't seen the function invoked but I saw "port->icount.overrun"
>> being incremented. This shouldn't happen. So I am a little puzzled here…
>Yeah, that's weird. Do you have a break-out box to confirm that RTS/CTS are
>being driven?

- beagle board
  According to schematics the board has only RX and TX connected. No

- am335x-evm
  The schematics say "DNI" next to a resistor on RTS/CTS. DNI stands
  most likely for "Do Not Install". With a scope it looks like the the
  wire behind the MAX is open.

- beagle bone black
  Only RX and TX are wired towards the USB2serial device.

In short: each device I have has RTS/CTS not working/connected and I
can't test HW handshake with HW available.

>Peter Hurley


More information about the linux-arm-kernel mailing list