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From: Jeffrey Walton <noloader@gmail.com>
To: linux-usb@vger.kernel.org
Subject: Re: CH341 driver and the 5.4 kernel
Date: Wed, 7 Jul 2021 17:48:48 -0400	[thread overview]
Message-ID: <CAH8yC8nqqwcn0xXgKpzum-4YHkaX+YAMdVfaL_2yHyuNteU1BA@mail.gmail.com> (raw)
In-Reply-To: <CAH8yC8=9arZhsPruxMmT+NL65=-YB57Mzg0fVfRdjMy5bmBbdg@mail.gmail.com>

> I'm trying to track down the cause of some garbage in a response when
> using an ELM327 (https://www.elmelectronics.com/ic/elm327/) with a
> CH341 serial controller.

To follow up on this...

Here's the device I am working with: OBD2 Scanner Adapter OBD2 ELM327
USB Cable Car Code Reader Diagnostic Scan Tool v1.5,
https://www.amazon.com/gp/product/B0897G6BMZ. It has a controller for
interfacing with a vehicle's OBD II, and a CH340 for USB
communications.

I contacted ELM Electronics Support [1] about the garbage I was
seeing. I thought I may have the serial port misconfigured in a subtle
way. Support wrote back that they did not make the OBD controller in a
v1.5. They make, among others, v1.4b and v2.0 [2]. It appears the OBD
chip is a knockoff.

I also think I tracked down the vendor for the CH340. It is a company
called WCH. It looks like they provide a GPL'd driver for Linux [3]
and name the driver ch34x. The driver is a lot different than the one
provided by the Linux kernel [4].

What I don't know is, if the WCH serial controller is another
knock-off. If it is an ill-performing knock-off, then that may explain
the problems using the existing Linux driver. Using the WCH driver
probably explains why things work under Windows. The WCH driver may
fix the problems I am seeing under Linux.

Jeff

[1] https://www.elmelectronics.com/ic/elm327/
[2] https://www.elmelectronics.com/wp-content/uploads/2020/05/AT_Command_Table.pdf
[3] http://wch-ic.com/downloads/CH341SER_LINUX_ZIP.html
[4] https://github.com/torvalds/linux/blob/master/drivers/usb/serial/ch341.c

  parent reply	other threads:[~2021-07-07 21:49 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07  7:33 CH341 driver and the 5.4 kernel Jeffrey Walton
2021-07-07  7:41 ` Greg KH
2021-07-07  7:56   ` Jeffrey Walton
2021-07-07 10:46     ` Greg KH
2021-07-07 14:45 ` Alan Stern
2021-07-07 21:55   ` Jeffrey Walton
2021-07-07 21:48 ` Jeffrey Walton [this message]
2021-07-08  6:17   ` Greg KH

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