Bug 727610
| Summary: | acm/ttyACM0/cdc_acm does not deliver data | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Arne Woerner <arne_woerner> |
| Component: | kernel | Assignee: | Kernel Maintainer List <kernel-maint> |
| Status: | CLOSED NOTABUG | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | high | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | 15 | CC: | gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2011-11-22 06:37:00 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description
Arne Woerner
2011-08-02 15:20:11 UTC
with 2.6.40.3-0 i still have those problems... on i686 it crashes after a few minutes (no ethernet access... it is head-less, so that i cant c any special error messages...)... -arne 2.6.40.4-5.fc15.x86_64 still doesnt like my USB device... -arne 2.6.40.6-0.fc15.x86_64 still doesnt treat my ttyACM devices as before... i had a closer look at it, and now it seems, that it holds back a byte in some buffer, so that a read fails... when a write a further byte, the following read delivers the byte that i expected before... i think that is a bug in the ACM or USB buffer handling, because: there is no guarantee that there is an infinitely long data stream coming from a serial port... -arne You should probably email upstream about this. We don't have the hardware to recreate issues and thus far you're the only person reporting a problem. at linux-kernel mailing list they suggested that the fedora-patches might have caused the trouble... i could falsify that theory (i used the fc15 kernel SRPM for 2.6.40.6-0 and hacked the SPECS file so that it would be a vanilla kernel (kernel-vanilla-2.6.40.6-0.local.fc15.x86_64.rpm))... furthermore i gave them some usbmon traces some days ago, but nobody replied yet (maybe they r angry, because i forgot the subject line once...)... a communication that works with both kernels (it is just about 1msec long): http://www.wgboome.org/cmd:P-C,2.6.40.6-0.local.fc15.x86_64.usbmon a communication that works with the 2.6.38.8 kernel but not the 2.6.40 kernel (it has a 50msec pause in the middle, where no USB stuff can be done... my self-tinkered-usb-device talks to some other device in that time, which takes its full concentration... but it is still a bug, that 1 byte hangs in some buffer, i think...): http://www.wgboome.org/cmd:Z-L-0,2.6.38.8-35.fc15.x86_64.usbmon http://www.wgboome.org/cmd:Z-L-0,1st-try,2.6.40.6-0.fc15.x86_64.usbmon http://www.wgboome.org/cmd:Z-L-0,2nd-try,2.6.40.6-0.fc15.x86_64.usbmon http://www.wgboome.org/cmd:Z-L-0,2nd-try,2.6.40.6-0.local.fc15.x86_64.usbmon -arne yesterday i made my self tinkered USB device more USB compliant... since then the current 2.6.41 kernel works fine... the TV sticks work fine again, 2... :-) -arne |