Re: CH341 driver and the 5.4 kernel

[Greg KH <greg@kroah.com>]

On Wed, Jul 07, 2021 at 05:48:48PM -0400, Jeffrey Walton wrote:
> > 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.

If you could try the latest 5.13 kernel release to let us know if that
solves the issues for you or not, that would be great as a lot of work
has recently gone in for these "odd" ch340-like devices.

thanks,

greg k-h