RFC : usbatm and iso

matthieu castet castet.matthieu at free.fr
Thu Jan 20 10:19:36 EST 2005


Roman Kagan wrote:
>   Salut Matthieu,
> On Wed, 2005-01-19 at 20:27 +0100, matthieu castet wrote:
>>I have started to add iso support to usbatm.
>>I have some questions.
> Me too :)  But of a bit more general nature, though:
> 1) I came across a site, http://www.eagle-usb.org , where they appear to
> have succeeded in using this modem with Linux.  Does their code work
> with your modem?  Have you looked at their stuff when developing yours?
yes, my stuff is based on their code. The goal is to made something we 
could integrate in the kernel later (actualy the module does everything 
: atm layer + fake ethernet device, ...).
The crc error are also present with this driver : 
> 2) From a quick look at their code, I understood that the modem could
> work using bulk endpoints only.  
There is a define USEBULK for the switch, iso is the default mode.

> Have you succeeded to get your modem to
> work in this mode with the current bulk-only usb_atm?
yes it works, except some unloading problem : when I try to unload 
usb-atm, the kernel freeze.
The usb-atm in iso mode works well, except also for unloading : when 
unloading the device driver, I have a kernel panic.

> I think it makes more sense to try to use usb_atm in its current state
> first, as it has been tested by several drivers already (even though it
> may give you lower speed than isochronous mode) and, once it works, try
> to extend it.
Yes I will track the unloading isue, but the some of my questions were 
general and also valid for bulk mode (resumitting directly empty urbs, 
filling the urb in init + just change buffer and context, ...)

> Bon courage,
>   Roman.


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