From: Clemens Ladisch <clemens@ladisch.de>
To: "Raphaël Doursenaud" <rdoursenaud@free.fr>
Cc: alsa-devel@alsa-project.org
Subject: Re: snd-usb-audio for Radikal Technologies SAC-2K
Date: Wed, 20 Oct 2010 11:29:14 +0200 [thread overview]
Message-ID: <4CBEB66A.5040005@ladisch.de> (raw)
In-Reply-To: <4CBEA2A5.7070902@free.fr>
Raphaël Doursenaud wrote:
> First, I more or less get the picture of what the code is doing but
> there's one part I fiddled with that I don't understand fully. What are
> the .out_cables and .in_cables bitmasks doing besides defining the
> number of ports ?
The also define the port numbers.
> Next, the input part seem to work flawlessly on all ports, but I have
> what seems to be a buffer overflow on the device when outputting midi
> data. Comparing the windows and linux usb traffic, something obvious
> shows up : the windows driver seem to be waiting for the device's
> acknowledgment after each sent byte before sending the next one while
> the snd-usb-audio module sends a bunch of bytes at once that ends up
> confusing the device _and_ module.
Do you mean that the Windows driver does not submit more than one URB
at once? And that it never puts more than one byte for a port into
one packet? Is it possible that the device want a F5 port number at
the beginning of every packet?
Anyway, all bulk packets must be explicitly accepted by a device,
so if the SAC-2K accepts a packet and then does something wrong,
it's the device's fault.
To force the driver to submit no more than one packet at once,
replace OUTPUT_URBS with a variable and set it to 1 for this device.
Regards,
Clemens
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next prev parent reply other threads:[~2010-10-20 9:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-20 8:04 snd-usb-audio for Radikal Technologies SAC-2K Raphaël Doursenaud
2010-10-20 9:29 ` Clemens Ladisch [this message]
2010-10-20 11:10 ` Raphaël Doursenaud
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