Hello,
I just got a NanoKontrol Studio and I'm experiencing the same
problems/symptoms as Robert did back in May.
I get both "MIDI I/O: Failed to read initial request" in the logs, and
frequent disconnects.
I've tried playing around with MinInterval/MaxInterval (as well as
Latency and Timeout) as suggested by Felipe, but I can't seem to get it
working properly.
However, by the logs from btmon, hcidump and bluetoothd, it seems like
the main problem is that I keep getting timeouts, and Bluez disconnects
for that reason.
The best result so far is that the midi device ports have appeared
briefly in aseqdump / Catia (not the CAD package, the one from KXStudio),
so it would seem there is a chance to get this working if I can just
prevent the timeouts/disconnections.
I've tried reading up a bit on what exactly the parameters do, and sort
of get the idea, but the details are still a bit hazy.
I'm just not sure how to proceed in the most rational way at this point.
(Blindly trying arbitrary numbers is probably not going to work well :) )
My questions are:
@Robert:
Did you get your nanoKontrol Studio to connect/work properly in the end?
If so, would you care to share which Connection Parameters you used?
@Felipe:
Is there any point in pursuing this at the moment, or do you think "MIDI
I/O: Failed to read initial request" might be a showstopper?
This is my understanding so far;
The interval values are multiplied by 1.25 to get the actual millisecond
value, thus 6 => 7.5 ms.
The latency value is the number of non-responses the stack will tolerate
before giving up on the connection.
The timeout value is in 10 ms increments, so for example 200 => 2000 ms
timeout.
Is the above correct?
Are the rules in chapter 3.6 of Apples design guidelines relevant, or
are they not applicable to the Bluez stack?
(https://developer.apple.com/hardwaredrivers/BluetoothDesignGuidelines.pdf.
I made a spreadsheet to test for legal combinations, it seems the valid
ranges are pretty narrow)
Finally, should I just try bumping MaxInterval (and maybe MinInterval)
until I see a change in behavior,
and leave Latency and Timeout at 0/200?
(I suppose I’ve changed the values a bit haphazardly up til now, a more
methodical approach might help, I’ll give that a try.)
I can see that changing timeout changes the period between disconnects,
but I can't seem to increase it enough to have them go away.
Many thanks for your work on this, and any help will be greatly appreciated.
Best regards
/Andreas
PS. I'm running Debian testing/unstable, Bluez 5.45-1, kernel is
4.11.0-2-rt-amd64, BT USB adapter is a Cambridge 0a12:0001, HCI 4.0.
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