Hi Remi,

Hi Laurent,

You will find my latest version of the CPM2 FHCI patch attached to this e=

-

mail. I've never bothered to clean it as we decided to drop the USB host
function from our device.

Thank you very much. Not clean is better than lost.

This depends on the disk. Some will probably not check the SOF token, oth=

ers

will do and behave strangely.

quoted

Also 40% seems quite a lot, even at 1000Hz interruptions, an idea how mu=

ch

quoted

does the CRC computation contribute in this CPU hogging ?

I haven't measured that, but probably not much. The biggest CPU time eate=

r

isn't the SOF generation interrupt but the USB packet handling code. The =

CPM2

USB host controller is really too low-level to be usable (except maybe fo=

r

specific applications). Comparing the OHCI/UHCI/EHCI and FHCI controllers=

 is

akin to  bit like comparing a full 16550 UART with a software bit-bang
implementation. You can get around with it, it might work for your specif=

ic

application, but you shouldn't try a full speed 115200bds communication w=

hile

computing a CPU-hungry physical simulation.

That's what I was afraid of. I now understand clearly why you didn't expect=
 that
much better performance with CPM3 in a past message
(http://ozlabs.org/pipermail/linuxppc-embedded/2008-May/030508.html).
Still, as you said, it can have some use for specific applications.

Do you remember the throughput you were able to reach with this cpu overhea=
d ?

Laurent Pinchart
CSE Semaphore Belgium

Kind regards,
R=E9mi Lef=E8vre