Red Hat Bugzilla – Bug 433889
Character loss on PL2303 devices after FC8 upgrade
Last modified: 2008-03-09 22:48:05 EDT
Description of problem: After updating a x86 based system using USB attached
serial devices (based on the PL2303 chipset) from FC6 to FC8, the system started
experiencing character loss on the serial ports.
Version-Release number of selected component (if applicable):
Fedora release 8 (Werewolf)
(also seen with kernel-18.104.22.168-42.fc8)
How reproducible: Very. Simply logging in via modem would show character loss
in the /etc/issue output. UUCP (I know, who still uses that?) was the hardest hit:
(2008-02-17 04:33:29.17 32027) ERROR: Timed out waiting for packet
(2008-02-17 04:33:29.17 32027) Errors: header 4, checksum 5, order 0, remote
(2008-02-17 05:03:38.47 4808) ERROR: Timed out waiting for packet
(2008-02-17 05:03:38.47 4808) Errors: header 2, checksum 4, order 0, remote
uucico sopwith mail (2008-02-17 05:18:42.42 4891) ERROR: Timed out waiting for
(2008-02-17 05:18:42.42 4891) Errors: header 0, checksum 0, order 0, remote
(2008-02-17 06:01:59.94 5111) Errors: header 0, checksum 0, order 0, remote
(2008-02-17 06:18:20.86 5162) ERROR: Timed out waiting for packet
Steps to Reproduce:
1. Install FC8
2. Attach a PL2303 USB serial device
3. Use it ;-)
No character loss.
Additional info: The problem has already been found and fixed upstream. Please
see the following changeset:
Here is the summary text for that changeset:
pl2303: Fix mode switching regression
Cleaning out all the incorrect 'no change made' checks for termios
settings showed up a problem with the PL2303. The hardware here seems to
lose sync and bits if you tell it to make no changes. This shows up with
a real world application.
To fix this the driver check for meaningful hardware changes is restored
but doing the tests correctly and as a tty layer function so it doesn't
get duplicated wrongly everywhere if other drivers turn out to need it.
Signed-off-by: Alan Cox <email@example.com>
Tested-by: Mirko Parthey <firstname.lastname@example.org>
Signed-off-by: Linus Torvalds <email@example.com>
I applied the referenced changes and built a test kernel. So far, so good. No
data loss. Please roll these changes into the next FC8 kernel as soon as
possible. I'll attach the patch I built my kernel from (based on the
Created attachment 295568 [details]
pl2303 patch from the upstream changeset
22.214.171.124-7 kernel is in updates-testing now with this patch already included.
Looks good. My system has been running fine with the latest kernel
(126.96.36.199-12.fc8). Feel free to close this one out. Thanks.