Dear Christoph,
2009/9/2 Zimmermann Christoph <christoph.zimmermann@xxxxxx>:
> hi gergely
>
> please read the mailing list archives before you ask a question.
> yes you are absolutely right, the behaviour you see is what we also reported here on the mailinglist. i'm a usbtmc driver user, not a kernel hacker, so i follow the mailing list and wait for patches to test.
Yes, I read the archives before posting and I've seen two messages in
the last few months with similar issues.
1) "Is anyone maintaining (or even using) usbtmc?" thread in the
beginning of August which ended with no conclusion, just a guess that
maybe the firmware is wrong. I know that it is not the case here.
2) "usbtmc driver" thread - I think by you in June, where with a
usbmon log, but then left the further questions unanswered (at least
they are not on the list).
I'm a user too, and and not a kernel hacker - yet. I'm asking because
I want to help fixing it, not just wait for a patch that will or will
not arrive. If there are a dozen people with the same issues, one
writes to the list while the others just sit around reading it and
don't make their voices heard, how the knowledgeable developers would
know what issues are important for more people?
I do apologize if it was a duplicate. I wrote it after reading the
archive because I thought I have sufficient extra information to
contribute.
>>I was testing the usbtmc driver with a number of Tektronix TD1012B
>>oscilloscopes that I could get my hands on in our lab.
>>It works to a certain degree, but is very unreliable. Since I couldn't
>>find a whole lot of documentation on how to interface it, I tried
>>similar things what Agilent wrote up [1] - though I know that driver
>>must be different from the current one that I use in 2.6.30.5. The
>>method is basically using the normal file handling routines on the
>>device file (e.g. /dev/usbtmc0):
>
> communicating with devices is the same, the ioctl functions are now sysfs files.
>
> in the mean time, you can still use the agilent driver you referenced. unload the mainline usbtmc module (rmmod) and use the load script from the agilent driver. works well on a 2.6.30 kernel.
Cheers, I'll check it out, see whether it works better and can find
the differences why the driver in the kernel does not work.
>>4)
>>Is there a buffer built in the kernel side somewhere? I see that the
>>data read is only possible in 1024byte portions.
>>E.g. retrieving a scan from the oscilloscope ("CURVE?" query) in
>>binary should return a 2507byte, or 5007byte length string (where the
>>last byte is the line-feed).
>>On windows, the Talker-Listener reads all this in one go, wheres on
>>linux I have to do multiple reads and stitch them together.
>>Also, there are quite a few times when (on Linux) I cannot read all
>>the data that I expect, and receive less then the required bytes.
>
> as i know, this works also with the agilent driver. i testet a lot sending big amount of data to the tmc device (>500mbyte).
> with tmc reads i haven't seen some 1024 byte limits.
>
Have you tested anything like this with the kernel driver? And I was
reading _from_ the device, not sending to it, so it might be
different. What device do you use? I couldn't see it in your message.
Thanks,
Gergely
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