[mythtv-users] Report: Watch out! UB435-Q V2 is NOT the same as UB435-Q

[Jarod Wilson]

On Oct 15, 2010, at 6:07 PM, Jarod Wilson wrote:

> On Fri, Oct 15, 2010 at 12:10 AM, Steven Willoughby <mythtv at thesteve.org> wrote:
>> Hello Mr. Wilson,
>> 
>>    Sorry for breaking the thread, I am new to the list as I just received my
>> V2 today.
>> 
>>    I have applied your patch [1] against the v4l-dvb source tree [2] but it
>> doesn't seem to work.  I get the following in dmesg:
>> 
>>  em28xx video device (1b80:e346): interface 0, class 255 found.
>>  em28xx This is an anciliary interface not used by the driver
>>  usbcore: registered new interface driver em28xx
>>  em28xx driver loaded
>> 
>>    It is quite possible that I am not testing it right.  I'm new to mythtv.
>>  I have tried using mplayer and tvtime but there isn't a /dev/video* device.
> 
> Nah, I'd expect to see way more spew than that if the stick was
> properly brought up, and the 'ancillary' stuff is unexpected. Means
> the quick hack patch isn't enough to get it working. Someone with the
> stick is going to have to experiment. Or they could guilt me into
> working on it by sending me a stick too (though I'm already backlogged
> with other hardware I really ought to be working on first...). ;)

So a spot of bad news here... I've been poking at one of Gavin's sticks inside a VM he set up for me, simultaneous with talking to one of the upstream em28xx driver authors. We now have a very good understanding of why the stick isn't working.

All known prior em28xx-based tuner sticks have had at least one isochronous usb endpoint, with a max packet size of 940 bytes, typically. This stick only has bulk usb endpoints and a max packet size of 512. Supporting this stick is actually going to require a fair bit of work in the em28xx driver core to support using bulk transfer instead of isochronous transfer.

Short version: don't buy this stick right now, its going to be a little while before its actually supported.

-- 
Jarod Wilson
jarod at wilsonet.com