Re: [PATCH] ar9170usb: add mode-switching for AVM Fritz!WLAN USB N devices in cdrom mode

[Frank Schaefer <schaefer.frank@gmx.net>]

Alan Stern schrieb:
> On Mon, 2 Nov 2009, Dan Williams wrote
>> In userspace, usb_modeswitch is the place to put all this logic.  Then
>> you tie it together with udev rules using some bubble-gum and duct-tape,
>> and maybe it works.  Of course, there's massive duplication of data
>> between usb_modeswitch and the kernel drivers, because the there's
>> simply no communication between the two.
>>     
> The only reason for this "massive" duplication is that nobody has
> bothered to remove from the kernel the parts that usb_modeswitch can
> handle.  Adding yet more switching code into the kernel, thereby
> _increasing_ the amount of duplication, seems like a bad idea.
>   
Or the other way around ;) .

Of course, we all don't want any duplicate code. We need a kernelspace
OR a userspace-solution.
But we should make pragmatic and device-(group-)specific decisions.
The hardware itself and the context in which it is used (=>
switch-policy) are too different.

...
> ... Jobs that can be handled 
> in userspace _should_ be handled there.
>
> Alan Stern
>   

Basically, I have no problem to agree here.
But what's the price we pay for this solution(s) in this case (and most
other devices with windows-driver-disc-mode) ?
You should not ignore the problems coming-up with the discussed
userspace-solutions.
This is not ONLY about technical aspects. We already discussed usability
and maintanance. Think about the whole product, not only the kernel-part.
Then, please, make a list of ALL pros and cons a make a pragmatic decision.

Frank