On Sunday 02 April 2006 1:05 am, Ethan Du wrote: > > I am currently working on CDC EEM. I would like to implement a CDC EEM > device. But I feel confused about CDC ECM and CDC EEM. As I see, both are > implemented by writing a pseudo network adapter driver for both the host > side and device side.
I don't know what you mean by "pseudo" here, but certainly drivers for both of them would be network adapter drivers. By the way, for clarity: "CDC ECM" is what Linux calls "CDC Ethernet". > The only difference is ECM extended a data class > interface. EEM doesn't. Is this the benefit of EEM? And is it more efficient > using less interfaces? If you look at EEM, it's clearly a bit less demanding than ECM in terms of hardware; it can work without altsettings. (The interrupt/status endpoint is optional for ECM.) Which means there's more choice for peripheral hardware. But it's a bit more demanding in terms of software, because adds all kind of funky (and not especially useful or necessary) in-band link control operations. Those happen to be a subset of the (not-useful-or-necessary) operations that clutter up drivers for Microsoft's RNDIS protocol; maybe one of the hidden goals for EEM was to make MSFT happier using a standard protocol. In my opinion, EEM is a lot more complex than it needed to be. ECM could have achieved the "more choice for peripheral hardware" goal by just removing the altsetting requirement; then it would be pretty much the "cdc_subset" that Linux uses to talk to hardware which can't support altsettings. > And for the driver on host side, I checked linux-2.6.13.1, and found it > only support ECM, there is no codes related to EEM packets. Are there > patches for linux to support EEM or are later version of linux support it > now? No, there's no host side support yet. In fact I've not even heard of a peripheral than needs EEM yet. To debug an EEM peripheral driver, you may well need to write the host side too. (Just add a module on top of the usbnet core.) - Dave ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
