Re: [LAU] Problems with usb midi cable

On Thu, Jun 18, 2009 at 4:57 AM, Clemens Ladisch<cladisch@email-addr-hidden> wrote:
> 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?
>
> 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".
> |
> | (*) 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
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>

Yeah, that's the case, really. Before I read your email, last night I
had the confirmation that is a hardware problem with the usb ports of
my laptop and the usb plug of the cable. I use a usb keyboard (not
musical) in my desktop and it has also two usb ports in one side. I
connected the keyboard to my laptop and connected the midi cable in
one of the usb ports of the keyboard. The uhci_hcd module was loaded
and no notes were lost. Another thing that happens is that only 2 usb
ports out of 4 of the laptop work with the midi cable, being that one
of them gives miscontacts (I need to force the cable into the port and
any sudden movement makes it disconnect).

I thank you all for your time. The sense that we don't know what is
wrong is very annoying, but now I can at least decide about something.
Maybe I should buy some decent midi interface :)

-- 
-------------------------------------------
Denis A. Altoe Falqueto
-------------------------------------------
Samuel Goldwyn  - "I'm willing to admit that I may not always be
right, but I am never wrong." -
http://www.brainyquote.com/quotes/authors/s/samuel_goldwyn.html
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