[linux-audio-dev] USB-MIDI Transfer rate

[Jens M Andreasen]

On Wed, 2005-09-21 at 18:31 +0200, Jens M Andreasen wrote:
> On Wed, 2005-09-21 at 09:54 +0200, Clemens Ladisch wrote:
> 
> > It seems the usb-midi driver grabbed the device first.  Disable it in
> > the kernel configuration, or put the line
> > 
> > usb-midi
> > 
> > into the /etc/hotplug/blacklist file.
> > 
> 
> Thankyou!
> 
> Now to get back to the subject. By changing
> 
>         ep->max_transfer = usb_maxpacket(umidi->chip->dev, pipe, 1);
> 
> in the snd_usbmidi_out_endpoint_create function in usbmidi.c to:
> 
>         ep->max_transfer = 512;
> 
> .. I get a 16 fold increase in thruput.
> 
> Test data was a SysEx dump for upgrading the firmware which used take
> ~25 sec, now ~1.6 sec. The cute little LCD progress animation isn't
> really visible anymore, but the update appears to be intact.
> 
> 
> 
> mvh // Jens M Andreasen
> 
> > 
> > HTH
> > Clemens
> > 
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