From: Scott Wood <scottwood@freescale.com>
To: Eran Duchan <pavius@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: Non-console UART issues with 8xx
Date: Fri, 15 Apr 2011 15:41:10 -0500 [thread overview]
Message-ID: <20110415154110.1b523da0@schlenkerla.am.freescale.net> (raw)
In-Reply-To: <BANLkTik=ivFpWQEhqrVnYfr2LS4HSnTDuA@mail.gmail.com>
On Fri, 15 Apr 2011 02:52:22 +0300
Eran Duchan <pavius@gmail.com> wrote:
> Hey list
>=20
> I have a custom MPC875 board running 2.6.37. SMC1 is the console, SCC4 is=
a
> general purpose UART (DTS is set up accordingly). No hardware or software
> flow control for either.
>=20
> The issue is simple: the non-console UART transmits garbled characters at
> the end of the transmission.
Hmm, there's a wait_closing field in uart_cpm_port that doesn't seem to be
initialized anywhere.
The driver should also be sending the STOP_TX/GRA_STOP_TX command *before*
clearing the transmit enable bits, rather than after.
> For example, set up SMC1 to console (works
> perfect) and SCC4 as non-console, run stty -F /dev/ttyCPM1 19200 raw and
> then echo -n 1234567890 > /dev/ttyCPM1 - transmission may be something li=
ke
> "1234567=C3=B8". Set the SCC4 as console (same baud rates) and the proble=
m is
> reversed (SCC4 works perfect, SMC1 transmit garbled).
>=20
> Rx direction seems fine, after some rudementary testing.
>=20
> I dived into the code and see that the console UART has a completely
> different initialization sequence than the non-console UART. Short of div=
ing
> into this ancient CPM architecture - does anyone have an idea?
The console is a bit different because it has a user that isn't tied to an
open file-handle -- which doesn't interact well with the driver's
(possibly misguided) desire to actually deconfigure the hardware when not
open.
-Scott
next prev parent reply other threads:[~2011-04-15 20:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-14 23:52 Non-console UART issues with 8xx Eran Duchan
2011-04-15 20:41 ` Scott Wood [this message]
2011-04-16 6:40 ` Eran Duchan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110415154110.1b523da0@schlenkerla.am.freescale.net \
--to=scottwood@freescale.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=pavius@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).