From: Laurent Vivier <Laurent@Vivier.EU>
To: Peter Hurley <peter@hurleysoftware.com>
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Jiri Slaby <jslaby@suse.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Seth Bollinger <sethb@digi.com>
Subject: Re: Broken serial port
Date: Tue, 17 Jun 2014 23:05:23 +0200 [thread overview]
Message-ID: <53A0AD93.7080705@Vivier.EU> (raw)
In-Reply-To: <53A096C2.7060800@hurleysoftware.com>
[-- Attachment #1: Type: text/plain, Size: 1942 bytes --]
Le 17/06/2014 21:28, Peter Hurley a écrit :
> On 06/17/2014 02:48 PM, Laurent Vivier wrote:
>> Hi,
>>
>> I'm not subscribed to these mailing lists, so CC: me.
>>
>> I'm playing for some days with a kernel 3.15 on an old mac performa 575
>> and it seems that the serial port is broken. When I log on using the
>> console on the serial port it seems there is an screen refresh added
>> after each character I send.
>
> What uart driver is this happening on?
>
> This is a known bug being worked on for these uart drivers:
> sunsab
> sunzilog
> ip22zilog
> pmac_zilog
Seems to be pmac_zilog, from dmesg :
pmac_zilog: 0.6 (Benjamin Herrenschmidt <benh@kernel.crashing.org>)
scc.0: ttyS0 at MMIO 0x50f0c022 (irq = 4, base_baud = 230400) is a
Z85c30 ESCC -
Serial port
scc.1: ttyS1 at MMIO 0x50f0c020 (irq = 4, base_baud = 230400) is a
Z85c30 ESCC -
Serial port
If needed, I can test the fix.
Thank you.
Regards,
Laurent
> Regards,
> Peter Hurley
>
>> A little demo :
>>
>> http://asciinema.org/a/10211 [at 3:20]
>>
>> I bisect and I found this commit :
>>
>> commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c
>> Author: Seth Bollinger <sethb@digi.com>
>> Date: Tue Mar 25 12:55:37 2014 -0500
>>
>> serial_core: Fix conditional start_tx on ring buffer not empty
>>
>> If the serial_core ring buffer empties just as the tty layer
>> receives
>> an XOFF, then start_tx will never be called when the tty layer
>> receives an XON as the serial_core ring buffer is empty. This will
>> possibly leave a few bytes trapped in the fifo for drivers that
>> disable the transmitter when flow controlled.
>>
>> Signed-off-by: Seth Bollinger <sethb@digi.com>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>
>>
>> If I revert it, all works fine :
>>
>> http://asciinema.org/a/10212
>>
>> Regards,
>> Laurent
>>
>
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 246 bytes --]
prev parent reply other threads:[~2014-06-17 21:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-17 18:48 Broken serial port Laurent Vivier
2014-06-17 19:28 ` Peter Hurley
2014-06-17 21:05 ` Laurent Vivier [this message]
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=53A0AD93.7080705@Vivier.EU \
--to=laurent@vivier.eu \
--cc=gregkh@linuxfoundation.org \
--cc=jslaby@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=peter@hurleysoftware.com \
--cc=sethb@digi.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).