From: Lukas Wunner <lukas@wunner.de>
To: Roosen Henri <Henri.Roosen@ginzinger.com>
Cc: "jirislaby@kernel.org" <jirislaby@kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"chao.zeng@siemens.com" <chao.zeng@siemens.com>,
"LinoSanfilippo@gmx.de" <LinoSanfilippo@gmx.de>,
"baocheng_su@163.com" <baocheng_su@163.com>,
"p.rosenberger@kunbus.com" <p.rosenberger@kunbus.com>,
"baocheng.su@siemens.com" <baocheng.su@siemens.com>,
"rgc@hms.se" <rgc@hms.se>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
"jan.kiszka@siemens.com" <jan.kiszka@siemens.com>
Subject: Re: [PATCH] serial: Fix incorrect rs485 polarity on uart open
Date: Thu, 4 Aug 2022 17:52:10 +0200 [thread overview]
Message-ID: <20220804155210.GA350@wunner.de> (raw)
In-Reply-To: <8f538a8903795f22f9acc94a9a31b03c9c4ccacb.camel@ginzinger.com>
On Thu, Aug 04, 2022 at 02:38:23PM +0000, Roosen Henri wrote:
> unfortunately this commit, which has been backported to v5.4.x, seems
> to break RS485 functionality on our iMX boards.
What exactly broke? Are you seeing incorrect polarity after opening
the tty but correct polarity after the first send? Or is polarity
always incorrect?
There have been reports about incorrect polarity after open and
before the first send as a result of that committ, but they only
concern a subset of drivers using the "em485" software emulation
in 8250_port.c:
https://lore.kernel.org/linux-serial/20220329085050.311408-1-matthias.schiffer@ew.tq-group.com/
imx.c does not use the em485 software emulation but rather a
dedicated GPIO, and the way you've set it up looks correct to me.
Some transceivers have both a DE and a !DE pin. Is the GPIO
connected to the former?
Thanks,
Lukas
next prev parent reply other threads:[~2022-08-04 15:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-18 9:58 [PATCH] serial: Fix incorrect rs485 polarity on uart open Lukas Wunner
2021-12-20 6:28 ` Jiri Slaby
2021-12-20 6:30 ` Jiri Slaby
2021-12-27 13:17 ` Lukas Wunner
2022-08-04 14:38 ` Roosen Henri
2022-08-04 15:52 ` Lukas Wunner [this message]
2022-08-04 16:11 ` Roosen Henri
2022-08-05 8:18 ` Lukas Wunner
[not found] ` <33b4b797-cd4a-436e-8e03-4bc5d7dd69ff.d000f9d8-ed3e-456c-b23a-5a86eac57608.c023ef82-f7f7-4a43-92f1-8642a4f822e1@emailsignatures365.codetwo.com>
[not found] ` <33b4b797-cd4a-436e-8e03-4bc5d7dd69ff.0668d69a-b7f6-4fc6-94cd-e3b904d4ce63.488ca449-4f1c-444b-8de0-1344d3aeb879@emailsignatures365.codetwo.com>
2022-08-05 11:20 ` Roosen Henri
2022-08-11 6:18 ` Lukas Wunner
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