Re: false positive -ENOSPC in ohci-q

On Mon, Feb 26, 2007 at 09:36:55AM -0800, David Brownell wrote:
> That's not a heuristic ... as I assume you know.  No guesswork

You assume wrong, I know nothing about that code, I simply hacked
around until the error gone away so I could use zoneminder while
still connected to internet ;).

> or nondeterministic behavior involved; just straightforward
> implementation of a bog-standard USB requirement.  Which nobody
> else has *EVER* complained about, note.

I've 5 usb devices attached, not just the camera and the usb modem and
they're all active at the same time. It might be possible that if I
disable some other usb device, then the logic would work again, I
don't know what the code is doing exactly. All I know is that things
are working fine after disabling that. I get zero usb related warnings
or errors. The USB is on board of a M2NPV-VM.

> > that clearly 
> > can choke in practice with real life usage (I can also imagine
> > hardware advertising a peak value, but if run in certain modes, like
> > with low res, generating lower max-values,
> 
> Then it would use a different configuration, different ISO endpoints,
> different bandwidth reservation.

The resolution is choosed with the ioctl _after_ opening the device,
this the open syscall failing so there's no chance for the kernel to
even know what the peak usage of the camera will be, unless it _first_
allows zoneminder to open the device (so than it can run the proper
ioctl setting the format and the resolution of the video grab).

> Sure I can.  Does the camera work by itself?  Evidently.  How about

You can blame on me, but that doesn't make you right.

> the modem?  Ditto.  The config that's disallowed would be both of
> them working at the same time.  Bug == trying that config.

And would you then please explain why the bug goes away with my patch? ;)

It is not a bug to try that config, because I'm telling you that if
you receive this email, it means that such configuration works
perfectly. If I would follow your suggestion, backout my patch, and
reboot the system, you would stop receiving emails because the modem
wouldn't connect anymore after zoneminder started analyzing its number
of frames per second of images from the camera.

Note that I can maintain this stuff in a local branch, I already do
for a number of other things anyway. I just though people would
appreciate to know if you get -ENOSPC and you apply my patch, you've a
chance that things will work fine. If this information is worthless
I'll stop wasting time here.

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