Re: [LAU] Problems with usb midi cable

> 75 means EOVERFLOW. linux/Documentation/usb/error-codes.txt says:
> | -EOVERFLOW (*) The amount of data returned by the endpoint was
> | greater than either the max packet size of the
> | endpoint or the remaining buffer size. "Babble".

Are you running any application on your system or just aseqdump? You
might find that if you are running a phat softsynth in realtime mode that
it is chewing up chunks of CPU when note events occur and preventing
the USB from being serviced?

You might also want to look at whether your CPU governor is 'ondemand'
rather than performance although even having said that, if the CPU had
stepped down to just 600MHz as my laptop does, that is still 100M cycles
per MIDI event which is more than aseqdump would need. Typically.

Have you looked at the version of the ALSA drivers? Just to make sure
that the drivers are servicing the input buffer correctly, emptying it in a
timely fashion.

Regards, nick.

"we have to make sure the old choice [Windows] doesn't disappear”.
Jim Wong, president of IT products, Acer

> Date: Thu, 18 Jun 2009 09:57:11 +0200
> From: cladisch@email-addr-hidden
> To: linux-audio-user@email-addr-hidden
> Subject: Re: [LAU] Problems with usb midi cable
>
> Denis A. Altoé Falqueto wrote:
> > I've bought a (el cheapo) midi-usb cable so I can play my musical
> > keyboard (also el cheapo... but I'm no professional :)). The thing is
> > that when I try to use it in my laptop (Gigabyte W566U, ArchLinux 64
> > bits, up to date), it is not reliable. I play the keys and the midi
> > events are not delivered correctly. I'm using aseqdump to debug. For
> > example, I press 5 keys and see 5 key down events, but when I releas
> > them, only 2 o 3 note up events are shown. And if I play too many
> > notes, it just stops receiving any events from the device, dmesg show
> > a strange message "urb status -75" and reconnects the usb device.
>
> Is there also a message when single events are lost?
>

> |
> | (*) Error codes like -EPROTO, -EILSEQ and -EOVERFLOW normally indicate
> | hardware problems such as bad devices (including firmware) or cables.
>
> > I tested the same cable on my old desktop (Asus A7N8X-X motherboard,
> > nvidia MX440 graphics card, 5 years of intensive e loyal use,
> > ArchLinux 32 bits) and it works fine. The difference between the two
> > seems to be the usb module that handles the device. [...]
> > Does anyone has any suggestions on how can I force ohci_hcd to be
> > loaded before uhci_hcd? Or is it realy the problem?
>
> ohci_hcd works only with an OHCI controller; uhci_hcd works only with
> a UHCI controller. Loading the other one will not have any effect.
>
> If you really want to try a different driver, connect the interface
> through a USB 2.0 hub; this will be handled by ehci_hcd. But I guess
> this won't make any difference.
>
> What kernel version are you using on each machine?
>
> The ICH8M chip of your laptop isn't known for making USB problems.
> This might be a problem with a USB port (try another one) or the
> laptop's wiring.
>
>
> Best regards,
> Clemens
> _______________________________________________
> Linux-audio-user mailing list
> Linux-audio-user@email-addr-hidden
> http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user

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Received on Thu Jun 18 12:15:03 2009