Pegasos OHCI bug (was Re: PROBLEM: memory corrupting bug,

[pacman at kosh.dhis.org]

Segher Boessenkool writes:
> 
> >> > |1. How do I locate all usb nodes in the device tree?
> >> > |
> >> > |2. How do I know if a particular usb node is OHCI?
> 
> You look for compatible "usb-ohci".

There is no "compatible" there. I can probably use class-code since the
parent is a PCI bus.

> 
> But this doesn't help you.  You do not know yet if the
> problem happens for all usb-ohci; for example, it could be
> that you have the console output device on usb; or as another
> example, it could be that this firmware leaves all pci devices
> in some active state.
> 
> So as I see it you have only two options:
> 
> 1) Figure out what exactly is going on;

I thought we were past that. The startup sequence leaves the device in a bad
state (writing 1000 times per second to memory that the kernel believes is
not in use), so it needs to be given a reset command before the kernel tries
to use that memory.

> > The big question that I'm still stumbling over is how to access the device
> > registers. The "reg" property looks like this:
> 
> You should look at "assigned-addresses", not "reg".  Well,
> you first need to look at "reg" to figure out what entry
> in "assigned-addresses" to use.

The properties look like this:

/pci at 80000000/usb at 5/assigned-addresses
 02002810 00000000 80000000 00000000 00001000
/pci at 80000000/usb at 5/reg
 00002800 00000000 00000000 00000000 00000000
 02002810 00000000 00000000 00000000 00001000

I'm not sure how I'm supposed to know which entry from "reg" is the right
one. I've been guessing that it's the second one, since that one matches the
only entry in "assigned-addresses". It's supposed to go the other direction?

-- 
Alan Curry