[pvrusb2] Fwd: Re: [linux-usb-devel] Re: [Linux-usb-users] USB EHCI VIA disconnect problem
isely at isely.net
Fri Feb 3 22:52:29 CST 2006
On Sat, 4 Feb 2006, Helmut Toplitzer wrote:
> Just in case ....
> Maybe Ingo Flaschberger's idea should be the default (tolerating errors).
No, definitely not! That change is a hack designed to cover up symptoms
of a real problem going on in the system.
Alan Stern <stern at rowland.harvard.edu> wrote:
> At this point I think you have to take it up with the pvrusb2 or mythtv
> developers. It looks like the program stopped as soon as it got a single
> error. It should be smart enough to retry the operation, perhaps after a
> short delay. Or reset the device if that doesn't work. And if nothing
> succeeds it should fail gracefully instead of just stopping.
This definitely does not involve MythTV, so take that out of the picture.
The pvrusb2 driver itself assumes that USB bulk transactions (which is
what it uses) are reliable and safe. It is not the place of a driver to
patch over misbehaving hardware which the driver otherwise has no
responsibility over. Now, with that said, certainly if the PVR USB2
device itself were causing this problem then it would make sense to do
something about it in the driver. But I'm far from convinced that the
hardware is doing this. The vast majority of people using the driver have
not had issues like these, and of the few that have had this (2? maybe 3
people?) there was other known suspect hardware in the system. So I'm not
convinced that the driver is not doing something that it should be doing.
> The log message from ehci-hcd says that there was some kind of error in
> the USB communication. The information isn't very specific, and it could
> be caused by something as simple as a poor-quality USB cable. Or it could
> be the device crashes.
I have seen this sort of thing with other USB devices where changing the
USB cable seemed to help. I've also seen other USB devices themselves
(e.g. certain older USB 2.0 hard drive enclosures) cause this sort of
problem. However to the best of my knowledge the PVR USB2 hardware is
reliable and should not be a source for this sort of trouble. It might be
possible that your particular device is having trouble (heck, that's
always a possibility, however remote). Unfortunately I can't suggest
anything useful to prove or disprove that :-(
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