[alsa-devel] usb-usx2y: playback fails with Tascam US122 on kernel 3.14

[Takashi Iwai]

At Wed, 06 Aug 2014 19:19:22 +0200,
Daniel Mack wrote:
> 
> On 08/06/2014 06:43 PM, Dr Nicholas J Bailey wrote:
> > On Thursday 26 June 2014 15:51:54 Dr Nicholas J Bailey wrote:
> >> I am having trouble with the US122 in playback and duplex mode. In capture
> >> mode, it is working.
> >>
> >> This problem occurs on (at least)
> >> Linux arial 3.14-1-686-pae #1 SMP Debian 3.14.7-1 (2014-06-16) i686
> >> GNU/Linux
> >>
> > Further information:
> > 
> > Using this kernel:
> > 
> > Linux arial 3.14-2-686-pae #1 SMP Debian 3.14.13-2 (2014-07-24) i686 GNU/Linux
> > 
> > trying to use the US-122 Tascam box results in the following showing up in 
> > dmesg. I have unplugged and reconnected the box twice to get the LEDs to light 
> > up. This has been the normal behaviour for as long as I can remember. You can 
> > only use the Tascam as capture device on this kernel.
> > 
> > Using this kernel:
> > 
> > Linux arial 3.10.11 #1 SMP Wed Oct 2 19:26:59 BST 2013 i686 GNU/Linux
> > 
> > the US-122 works fine for simultaneous capture and playback.
> > 
> > I've looked at the difference in the source code between 3.10 and 4.14 and 
> > there is very little in the usb-usx2y alsa module. Is there some midi-related 
> > change I should know about?
> 
> This driver is unfortunately poorly supported by the community. Very few
> people have such a device, the driver has ample areas it needs cleanups
> in, and the original author is unfortunately unresponsive.
> 
> The best thing you can do is probably bisect the issue:
> 
>   https://wiki.ubuntu.com/Kernel/KernelBisection

Right.  My guess is rather the changes in USB driver side.
So, better to bisect in the full path, not limited to sound/*.


Takashi

> > I understand that the US-122 is a usb-1.1 device and I have the ehci module 
> > loaded, but it was there too with the older kernel and that worked fine.
> 
> Yes, that shouldn't be an issue. Let us know what the bisection tells you.
> 
> 
> Daniel
> 
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