Re: USB?

[Sven Luther <sven.luther@wanadoo.fr>]

On Mon, Jun 26, 2006 at 07:49:50PM +0200, Dieter Schuster wrote:
> Hi,
> 
> am So, den 25 Juni 2006, schrieb dtutty@porchlight.ca:
> > Is there a way to add USB to a unit that doesn't have it? 
> 
> I think it would help if you tell us the System you have. 
> 
> > Can a generic USB PCI card go in a slot or will the firmware barf?  Will
> > Linux see it?
> 
> On the Pegasos II (a PowerPC system from Genesi/bplan with a G3 or
> G4) there seems to be some problems with USB cards. I have one working
> (it has a VIA chip). But my SCSI card, which works on a x86 system
> does not work in my Pegasos II.

USB cards work just fine on pegasos. There was a bug concerning the USB 2.0
driver in an older firmware version, which caused the dma engine to not be
quiesced, but apart from that it works just fine.

The only risk that can happen, is that the IBM firmware doesn't support
booting from the USB mass-storage devices, but once in linux, there should be
no problem.

Your SCSI card is another issue, it may do DMA stuff inside the bios, and thus
play unnice tricks with the firmware emulation.

If you had a scsi card with a forth bios, it would probably work just fine,
both on pegasos and on IBM CHRP boxes.

> I cannot tell you something about PCI on other PPC systems.

Basically, all cards which don't need a bios/firmware, will work just fine.

> > IBM's description of PCI says that its architecture-independant, which
> > suggests that this should work if the PPC kernel has USB.  However, the
> > diagnostic manual lists as one of the errors that an installed PCI card
> > doesn't have a recognized VPD.
> 
> It seems that not all PCI cards are architecture-independant, in
> particular those with a "big" firmware.

Indeed.

Friendly,

Sven Luther