Messages in this thread | | | Date | Wed, 28 Apr 2010 13:41:09 +0200 | From | Josua Dietze <> | Subject | Re: USB gadget with drivers "on board" |
| |
Michał Nazarewicz schrieb: > On Mon, 26 Apr 2010 22:14:54 +0200, Josua Dietze > <digidietze@draisberghof.de> wrote: > >> Important for the Linux handling is that "mode 1" is clearly >> distinguishable from "mode 2", either by using a different product ID >> or by setting a different class for the device or interface 0 (will >> most likely be "8" for the install mode). > > So it will be enough to change the USB device class for the zeroth > interface for udev to recognise the mass storage to be ejected? Note > that I will use mass storage in the second mode as well.
This is often the case with the common "zero-cd" devices, but they have the storage on upper interface numbers after switching.
The point is to enable udev or any other tool to distinguish between "unswitched" and "switched"; otherwise the procedure for switching will be executed on *both* modes which might disturb the device or the system.
A change in one of the attributes like iProduct or iSerial could be detected as well of course.
> Also, I think that it might be a good idea to make some "standardised" > mechanism for all such devices so that a generic udev code could be > written. Adding things to the descriptors may be difficult in a way, > but maybe adding "[NoCD]" to the interface name would be enough.
That is up to the (countless) manufacturers of course; on the other hand, the Windows drivers need to recognize the mode as well so there should always be one way or the other to accomplish that.
Josua Dietze -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |