max 16 hci devices on usb 2.0

max 16 hci devices on usb 2.0

[Bram Jansen]

Hi,

I have a question regarding the connection of 16 hci devices to a linux box.
I've been looking around for quite some time and I was not able to find
something useful, therefore I hope anyone of you guys is able to point me in
the right direction.

We have used quite a few kernel versions to try to connect 16 hci devices to
one system with usb 2.0 enabled.
This gives a problem after 7 devices. Devices hci7-hci15 give timeouts and
errors after initializing.

We solved this problem by disabling ehci in the kernel, so the bluetooth had
to use usb 1.1 (ohci)
with these settings it works without any problems and all 16 hci devices are
initialized properly after insertion/boot

now there has come the need for usb 2.0 on the same system.

Is there a known solution for this issue?

Thanks in advance,

Regards,

Bram Jansen

Re: max 16 hci devices on usb 2.0

[Marcel Holtmann]

Hi Bram,

> I have a question regarding the connection of 16 hci devices to a linux box.
> I've been looking around for quite some time and I was not able to find
> something useful, therefore I hope anyone of you guys is able to point me in
> the right direction.
> 
> We have used quite a few kernel versions to try to connect 16 hci devices to
> one system with usb 2.0 enabled.
> This gives a problem after 7 devices. Devices hci7-hci15 give timeouts and
> errors after initializing.
> 
> We solved this problem by disabling ehci in the kernel, so the bluetooth had
> to use usb 1.1 (ohci)
> with these settings it works without any problems and all 16 hci devices are
> initialized properly after insertion/boot
> 
> now there has come the need for usb 2.0 on the same system.
> 
> Is there a known solution for this issue?

you better ask such questions on the Linux USB mailing list since I have
no idea why sometimes the hubs causes problems.

As a side note. The 16 HCI devices limit is not fixed actually. You can
just compile your own libbluetooth with a different limit. The kernel
supports as many devices as you have memory :)

Regards

Marcel