Bug 1235715

Created attachment 1043166 [details]
Output of lsusb -v -d 1a86:7523

Created attachment 1043167 [details]
Real output of lsusb -v -d 1a86:7523

Previous attachment was wrong (no "-v" option).

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Still is present at least in F22 with 4.2 kernel, so likely on F23 too.

Still applies to F23 with kernel 4.4.2-301.fc23.x86_64

This still has not been fixed.

Fedora 23:
[1209987.585301] usb 2-1.4: new full-speed USB device number 7 using ehci-pci
[1209987.671459] usb 2-1.4: New USB device found, idVendor=1a86, idProduct=7523
[1209987.671464] usb 2-1.4: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[1209987.671466] usb 2-1.4: Product: USB2.0-Ser!
[1209987.671831] ch341 2-1.4:1.0: ch341-uart converter detected
[1209987.673916] usb 2-1.4: ch341-uart converter now attached to ttyUSB0

# uname -a
Linux fedora23 4.5.7-202.fc23.x86_64 #1 SMP Tue Jun 28 18:22:51 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Still applies to F23 with kernel 4.5.7-202.fc23.x86_64

=====

Fedora 24:
[ 1208.222677] usb 2-1.3: new full-speed USB device number 5 using ehci-pci
[ 1208.309453] usb 2-1.3: New USB device found, idVendor=1a86, 
idProduct=7523
[ 1208.309463] usb 2-1.3: New USB device strings: Mfr=0, Product=2, 
SerialNumber=0
[ 1208.309469] usb 2-1.3: Product: USB2.0-Ser!
[ 1208.351738] usbcore: registered new interface driver ch341
[ 1208.351786] usbserial: USB Serial support registered for ch341-uart
[ 1208.351820] ch341 2-1.3:1.0: ch341-uart converter detected
[ 1208.354803] usb 2-1.3: ch341-uart converter now attached to ttyUSB0
[root@dell:~]# ver
Fedora release 24 (Twenty Four)

Linux fedora24.localdomain 4.6.4-301.fc24.x86_64 #1 SMP Tue Jul 12 11:50:00 
UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Still applies to F24 with kernel 4.6.4-301.fc24.x86_64

====

There is *some* communication that can be observed (e.g. with Minicom), but the data is corrupted.  If you bridge the RX and TX pins on the adapter, for instance, garbage is echoed back rather than the characters you typed.

Looking through bugzilla, it seems that Bug 1323328 might be a duplicate of this issue.
https://bugzilla.redhat.com/show_bug.cgi?id=1323328

*********** MASS BUG UPDATE **************
 
We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 24 kernel bugs.
 
Fedora 24 has now been rebased to 4.7.4-200.fc24.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.
 
If you have moved on to Fedora 25, and are still experiencing this issue, please change the version to Fedora 25.
 
If you experience different issues, please open a new bug report for those.

This bug still exists with kernels 
4.7.3.200-fc24.x86_64 and 
4.7.4.200-fc24.x86_64

This bug still exists with kernel 4.7.5.200-fc24.x86_64

This has not been fixed with the Fedora 25 Beta 1 release.

Kernel 4.8.0-0.rc7.git0.1.fc25.x86_64

USB-Serial Adapter
driver: ch341
idVendor=1a86, idProduct=7523

The chipset is recognized, and the ch341 kernel module is loaded, but the baud rate is not set correctly, and so garbage is sent/received through the usb/serial adapter instead of valid characters (for instance with minicom).

*********** MASS BUG UPDATE **************

We apologize for the inconvenience.  There are a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 24 kernel bugs.

Fedora 25 has now been rebased to 4.10.9-100.fc24.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.

If you have moved on to Fedora 26, and are still experiencing this issue, please change the version to Fedora 26.

If you experience different issues, please open a new bug report for those.

*********** MASS BUG UPDATE **************
This bug is being closed with INSUFFICIENT_DATA as there has not been a response in 2 weeks. If you are still experiencing this issue, please reopen and attach the 
relevant data from the latest kernel you are running and any data that might have been requested previously.

As of kernel-4.10.12-200.fc25.x86_64 this looks closed, after a raft of commits in the upstream kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/log/drivers/usb/serial/ch341.c

I tested it now, and must admit with great pleasure it seems to work as it should. Closed for me since kernel 4.10 or around that.

Agreed! Works now with Fedora 25 kernel 4.10.13-200.fc25.x86_84.  

Fantastic!! Thanks to all involved in fixing this.