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From: Laurent Pinchart <laurent.pinchart@tbox.biz>
To: Mike Rapoport <mike@compulab.co.il>
Subject: Re: CPM2 USB driver & MPC8248
Date: Tue, 7 Feb 2006 14:14:28 +0100
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> >When I connect a USB 2.0 Mass Storage device, initialization fails when
> > trying to fetch the string descriptors. Here's what USBMon produces (I
> > decoded the USB transactions with the device).
>
> [snip]
>
> I had similar problems with mass storage devices (disk-on-key). I've
> tried to find out what was causing them but I hadn't much success with it.
> I think that problem might be in driver performance because it is very
> far from optimal.

How is the driver development going ? You're not using the sourceforge CVS/SVN 
repository, is there another one somewhere (maybe a git tree) ? Are you 
actively working on performance issues, or is the development currently 
stalled ? What are the major performance issues ? I noticed that the driver 
uses the MPC82xx packet level interface. Why don't you use the transaction 
level interface ?

> Another thing that may cause problems is how storage devices treat SOF
> packets, but I'm not USB expert enough to be sure about that.

That might explain why some devices don't even respond to the first request. I 
noticed that, on my EP8248 board, the controller only sends 990 SOF packets 
per second (or rather 990 SOF interrupts are generated). I might have a time 
base problem somewhere, as I computed the number of interrupts per second 
with a simple

cat /proc/driver/m8xxhci_privateh > sof.1 && sleep 300 && 
cat /proc/driver/m8xxhci_privateh > sof.2

Do you have the same problem ? I'll see if I can get my hands on a USB 
protocol analyzer.

Laurent Pinchart