On 2012-11-03 17:50, Alan Stern wrote:
I get a USB disconnect of my external USB HDD about once per day.
Enabling USB debug in the kernel shows the first error as 'ehci_hcd
detected XactErr'. It happens only when the drive is idle. For
example,
I had a process writing on the HDD every 3 seconds and the problem
did
not occur for several weeks.
Correction: These errors do not occur when the drive is idle. You
can
see in the log you attached:
OK thanks for this. I then reformulate my statement: using the drive on
a frequent basis (3s period) prevents the problem from occuring.
No. The drive remains at full power as long as it is mounted. If
the
power level were changed, it would show up in your debugging log.
The current test is that I have been using it in OHCI-only mode for one
full day (by unloading the ehci kernel module) and result so far is that
I did not encounter the issue. Interestingly here is a quote from the
support team at pcengines.ch : "there are some known issues regarding
the Hi-speed USB modes. The system then reports dropping the device, EMI
troubles, and so on.
There are no other workarounds."
An interesting thread on this subject and on this very mailing list is
http://thread.gmane.org/gmane.linux.usb.general/36246 "Geode LX CS5536
EHCI problems". It is 2 years old but is about disconnects also. Does
anybody know if things have improved since then ?
It appears that the drive disconnected itself from the USB bus.
There's no indication of why this happened.
I conclude from all these that :
- we face some hardware issue probably related to the AMD CS5536 chip
(or less probably its use on the Alix board)
- playing with power management won't help
- problem is probably not new
- problem is most probably not solved at this point
Do I have to mourn the idea of using the USB 2.0 capabilities of the
board, given that the usage of this particular chip is probably too low
/ fixing is probably too hard to trigger enough interest in solving the
issue (and given that I probably cannot fix it all on my own) ?
Miguel
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