USB discussions getting a bit heated

From what I've read, it seems that the fundamental problem is that the BCM2835 SoC has a bare-bones USB host controller which requres a lot of the ARM processor.  Such a USB host controller works fine in BCM2835 intended applications, such as Roku, but if you try to use the ARM11 as a high-performance GNU/Linux engine talking to dozens of USB devices you will run into limitations.  It also sounds like documentation for the SoC's USB host controller is not available and that the low-level "open source" software suffers from "security through obscure code".  If this is indeed the case, it will be hard to improve things.

Please let me know if my impressions are incorrect.  I would be delighted to hear that open documentation for the USB host controller is available (link?) and that the low-level driver is perfectly understandable and well-documented (link?).

John Beetem wrote:

 

From what I've read, it seems that the fundamental problem is that the BCM2835 SoC has a bare-bones USB host controller which requres a lot of the ARM processor.  Such a USB host controller works fine in BCM2835 intended applications, such as Roku, but if you try to use the ARM11 as a high-performance GNU/Linux engine talking to dozens of USB devices you will run into limitations.  It also sounds like documentation for the SoC's USB host controller is not available and that the low-level "open source" software suffers from "security through obscure code".  If this is indeed the case, it will be hard to improve things.

This is EXACTLY the same conclusion that I have reached.

The Pi is in reality not a general purpose computer.  It's half a computer, with the ARM being used to fill in the hardware gaps that let the SoC be designed at the lowest possible cost.  If you try to use the ARM at the same time for normal computing, you can kiss your SoC's correct functioning goodbye.

It's this that is wreaking havoc when you attach a correctly-working self-powered hub with added devices downstream.  Linux accepts it, because it doesn't realize what the purpose of the ARM is within the BCM2835.  In reality it should say "Sorry Dave, I don't have the CPU headroom for that" and refuse to attach.

Morgaine.

it should say "Sorry Dave, I don't have the CPU headroom for that" and refuse to attach.

LOL...  but does sound work well enough for it to sing the song ?

it should say "Sorry Dave, I don't have the CPU headroom for that" and refuse to attach.

LOL...  but does sound work well enough for it to sing the song ?