[linux-dvb] Re: DVB-USB-T and 2.6

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Thursday 11 March 2004 01:44, John Dalgliesh wrote:
> On Thu, 11 Mar 2004, Andrew de Quincey wrote:
> > On Thursday 11 March 2004 00:19, John Dalgliesh wrote:
> > > So setting a configuration like that probably isn't what you want to do
> > > once you've matched to an interface - which the kernel 2.6 code looks
> > > like it does - although I guess it doesn't hurt if you only have one
> > > configuration anyway.
> > >
> > > As far as I can tell, the (conceptual) hierarchy of things USB goes:
> > > [USBDevice] x [configuration value] x [USBInterface] x [alternate
> > > setting] x [USBPipe]
> > >
> > > where the choice on a previous stage affects the options on the next
> > > ... but I'm a little hazy on the last couple of stages :)
> >
> > Actually, that would explain another weird phenomenon I was seeing; two
> > USB-Ts are showing up under 2.6, when I've only plugged one in. The first
> > works, the second doesn't. Maybe I should remove the
> > set/reset_configuration() call entirely?
>
> Yep, I reckon you should just remove that line (under 2.6) and see if it
> works :)

Yep, sounds good to me. And it did. I now have only one adapter :)

> Also I think you should use the 'probe' method to discard the interface
> that you don't want. According to the ttusb_setup_interfaces method it
> looks like it really wants to run as interface index #1. So if the
> usb_interface passed into probe isn't this index then it's not the one you
> want (and you don't need to call usb_set_interface either).

You're right about checking the interface number (I think).. just in case I 
get passed interface #0 (but I doubt I will; I guess the kernel claims that 
one for device configuration). The speedtch USB ADSL modem driver does this 
check in 2.6.

However, I think I do have to call usb_set_interface to choose the correct 
altsetting for interface 1. There seem to be loads of different possible 
altsettings for interface 1, so I'd better ensure the correct one is chosen.

> But then it doesn't really make sense why it should be the first device
> that works and the second that doesn't ... unless the ordering got
> reversed somewhere and 1st device != interface #0.

Could be anything really; it was definitely broken. My guess is it continued 
to do the code after usb_reset_configuration(), but then was called again due 
to the interface teardown. Its probably just luck the first device worked at 
all.

> > > btw the TT USB devices do seem to have two USBInterfaces however...
> >
> > Yep.. I assume one default interface, and one for when its up and
> > running.
>
> Not sure, I think one is some sort of device setup interface, and the
> other is where the real action happens. But that is just a guess.

Seems to fit with with what I vaguely remember about USB.


-- 
Info:
To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb" as subject.