From mboxrd@z Thu Jan  1 00:00:00 1970
From: bigeasy@linutronix.de (Sebastian Andrzej Siewior)
Date: Mon, 29 Sep 2014 18:15:05 +0200
Subject: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround
 for AM33xx
In-Reply-To: <54197C99.8030601@hurleysoftware.com>
References: <1410377411-26656-1-git-send-email-bigeasy@linutronix.de>
 <1410377411-26656-10-git-send-email-bigeasy@linutronix.de>
 <20140911111721.GB17476@xps8300> <54118AAB.2010205@linutronix.de>
 <5411967A.6090406@hurleysoftware.com>
 <54119AAA.9080907@linutronix.de>
 <5411B33F.10405@hurleysoftware.com>
 <54171B85.5060209@linutronix.de> <54186B89.8050505@linutronix.de>
 <54197C99.8030601@hurleysoftware.com>
Message-ID: <20140929161505.GF13142@linutronix.de>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

* 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
  RTS/CTS

- 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.

>Regards,
>Peter Hurley

Sebastian