USB 3.0 - Newbee

[DD]

What is a meant by link, sublink and lane in terms of USB?

Can ypu explain the Streams concept in USB 3.0/3.1 ?

As per my understanding streams are buffers in endpoints. Is it correct?

How the Host controller selects which stream (ID)to use for sending data from Host to device?

[Jan Axelson]

In the USB 3.1 spec, Chapter 2 defines link, sublink, lane, stream pipe, and stream endpoint (and pipe and endpoint).

Section 4.4.6.4 explains the use of Stream IDs.

Let us know if you have further questions after reviewing these sections.

[DD]

Thanks Janet for the pointers.

Kindly correct my understanding.....

My understanding from USB 3.1 spec, Chapter 2
Lane = Tx->Rx.
SubLink = Aggregate(Lane).
Link = TX-Sublinks + Rx-Sublinks.

Queries
   Query 1. If there is only 1 Tx and RX , then Lane and sublink refers to the same thing?
   Query2. if a mobile/device is connected to a PC directly(including the root hub). What are the Lane /SubLink/Links?
                     Lane : Tx of root hub -> Rx of device. OR
                                Tx(USP) of root hub -> Rx of root hub(DSP) or
                                 Tx(DSP) of PC port -> Rx of device or
                                  All are considered as Lanes.
   Query3.  if the mobile/device is connected via hub(external hub),What are the Lane /SubLink/Links?
   Query4. What is the complete path from the Root Hub to the device called ?
   Query5. Why we need to differentiate between lane, sublinks and links? Where are these used?

[Jan Axelson]

Thanks Janet for the pointers.

Kindly correct my understanding.....

My understanding from USB 3.1 spec, Chapter 2
Lane = Tx->Rx.
SubLink = Aggregate(Lane).
Link = TX-Sublinks + Rx-Sublinks.

yes

Queries
   Query 1. If there is only 1 Tx and RX , then Lane and sublink refers to the same thing?

yes

   Query2. if a mobile/device is connected to a PC directly(including the root hub). What are the Lane /SubLink/Links?
                     Lane : Tx of root hub -> Rx of device. OR
                                Tx(USP) of root hub -> Rx of root hub(DSP) or
                                 Tx(DSP) of PC port -> Rx of device or
                                  All are considered as Lanes.

Do you mean UFP (upward facing port - toward the host) (not USP) and DFP (downward facing port - toward the device) (not USP)?

The root hub is at the top so it has a DFP whose two lanes, one in each direction, connect to a UFP on the device.

   Query3.  if the mobile/device is connected via hub(external hub),What are the Lane /SubLink/Links?

Each pair of ports has lanes. So there is one set of lanes between the hub's DFP and the device, and another set of lanes between the hub's UFP and the host.

   Query4. What is the complete path from the Root Hub to the device called ?

I don't know if the spec has a term for this. A pipe is "a logical abstraction representing the association between an endpoint on a device and software on the host" so the path could be considered a collection of one or more pipes.

   Query5. Why we need to differentiate between lane, sublinks and links? Where are these used?

You can see in the spec how the different terms are used. For example, it's helpful to be able to say "sublink" instead of "The collection Rx or Tx lanes between a DFP and a UFP."