xHCI (USB 3 Host) without companion controllers?

[ErikVikinger]

Hello,


i have read the xHCI Specification for USB 3 at it seams to me that there are no companion controllers.
Is it right?

If yes, that is good. It means that only one driver is needed for supporting all 4 speed grades.
And i can use all advantages of xHCI for all 4 speed grades (MSI is for me very important because i do not support the PCI-INTx-Signals).


Greetings
Erik

[Brynet-Inc]

Yes, xHCI seems to eliminate the need for UHCI/OHCI/EHCI controllers.. but that doesn't mean you won't find them, for example you may find USB 1.1/2.0-only ports integrated on a motherboard with a xHCI controller card installed by the user.

So you'll need UHCI/OHCI/EHCI and xHCI drivers, assuming you want USB to work on all possible hardware combinations.

[Owen]

Note that while xHCI doesn't /require/ companion controllers like USB 2.0 did (for directly connected devices - you can have a pure EHCI USB 2.0 port if there is a hub "glued onto" it) it also doesn't preclude their existance.

I think PCs will still have companion controllers for many years to come, so that existing OSes can use the ports (even if only at lower than maximum speed)

Not supporting PCI INTx signals seems like a flaw to me. Certainly it stuffs up supporting lots of the chipset inbuilt hardware for many of the machines I have.

[ErikVikinger]

Hello,


Thanks for Your answers. It is really comforting that i have the xHCI specification read correctly.


I do not plan to support the normal PC platform, i develop for a special platform and i can ensure that there are no OHCI/UHCI- and EHCI-Controllers (because i do never seen any of this with support for MSI or MSI-X, they can not working on my platform).

The decision for MSI/MSI-X was very simple, i do not want to support for shared IRQs. MSI/MSI-X does fits my wishes and the most of the better hardware do support it, thus it is the favored solution.

With the xHCI i get a complete solution for all USB thinks that fit all my needs for peace of mind (for the next time i really does not need the super speed performance, but all existing USB devices working with a single driver and without IRQ-sharing is fine).


Greetings
Erik

PS.: Sorry for my horrible English, my native languages are VHDL and german.