Difference Between USB Multi Interface, Multi Function, Composite andCompound Devices.

Hi,

1. I am very much confused about USB Multi Interface, MultiFunction,
Compound and Composite Devices. Can anyone please Clarify me the
difference.

2. I am writing a USB Bus Enumerator, i mean something similar to the
Host Controller Driver.
so, i wanted to invalidate the undelying devices to the OS. Now, i am
arised to a point, how to detect Multi Interface Devices.
i thought the device with multiple interfaces is a Multi interface
device, but i have couple of devices with me which are multiple
interfaces(2No's) but it is a single interface device. when i connect
it to the standard host controller it detects as single interface
device and the usbccgp.sys is NOT loaded. Here my question is how do i
detect whether or not the device is a Multi Interface device.

Thanks and Regards,
Neo

 

Hi,

i have figured out something, please confirm it.

Question : How do i detect whether or not the device is a Multi
Interface device.
Answer : Number of Interfaces are greater than 1 then it is a
MultiFunction Device.
But, i have found some of the devices having more than one interface
but the Windows Standard HC Showing them as Single Function Device.

So, i have debugged furthur and arrived to a conclusion that,
The Device Having more than one interface is MF Device.
But, though the device having Multiple Interface but with same Class,
Protocol, Sub Class is Single Function Device.

That means multiple interface devices having different Class,
SubClass, Protocol are only MultiFunction DEvice, otherwise it's
single function device.

please confirm it !

Thanks and Regards,
Neo

 

Nope. Hint: you changed the term in your answer from what it was in
your question.

Typically, multi-function devices have class/subclass/protocol of
0x00. Which is a special case of "they are all the same", I suppose.

 

Sorry, i Apologise for my mistake.
i should have checked thoroughly before postin it into the group. i
apologise for my mistake.

My question was :

Question : How do i detect whether or not the device is a Multi
Function device.
Answer : Number of Interfaces are greater than 1 then it is a
MultiFunction Device.
But, i have found some of the devices having more than one interface
but the Windows Standard HC Showing them as Single Function Device.

Regards,
Neo

 

This is how the Microsoft drivers do it:

http://msdn2.microsoft.com/en-us/library/aa476434.aspx

 

Remember that certain device classes are handled specially. USB Audio and
USB Video devices, for example, always have two interfaces (a control
interface and a streaming interface), but the hub driver knows that they
are related, and exposes only a single device for them.

 

My question was :

Hi,

Thank you very much Mr. Chris. It helped me a lot. Thanks once again.

Hi Mr. Tim Roberts,

The Issue here is i am writing a USB Enumerator, i.e., Complete
replacement for USB Host controller. Including usbport.sys, usbhub.sys
and usbxhci.sys.
so, i need handle it in my driver, as there is no usbhub.sys to handle
for me.
can you please shed some more light on how to handle devices like
them.


Thanks and Regards,
Neo

 

usbport.sys, usbhub.sys and usbccgp.sys are not part of the host
controller. You can probably use those as-is, even with a custom host
controller driver.

Haven't you ever watched how the real USB stack handles these devices? It's
not that hard to figure out.

 

Hi Mr. Tim Roberts,

how can i use them to make it work with my HC Driver.
can you please help in finding the documentation for the same,
how can i tell those drivers to use my Host controller but not the
standard windows driver.

Thanks and Regards,
Neo

 

The innards of the USB stack are not documented. Why are you creating
a replacement?

 

Remember that driver stacks work the other way around, from the bottom up.
As long as your host controller driver exposes hubs and devices using the
standard PnP ID names, the system will load the standard drivers to handle
them. It can't tell, nor does it care, what's underneath.