On 2016-11-18 11:25:26 [+0100], Oussama Ghorbel wrote:

Hi,

Hi,

I have written recently a patch that solve the FIQ issue with RT
Preempt on the 4-core Raspberry Pi board.
Please see this article for full description on the solution.
https://www.osadl.org/Single-View.111+M5c03315dc57.0.html

So you have ~13ms max latency without the patch but with disabled FIQ
and 170us with the Patch? Something does not look right.

Anyway. If you don't mind I added this information to the RT-wiki [0].
So lets hope google will point RPI users there.
Could please cross check if the information is correct and add other RPI
informations? I named it "Raspberry PI 3". I am not sure if the problem
is also relevant on "Raspberry PI" and "Raspberry PI 2".

One thing: The patch is against dwc_otg. Since v3.14 we have the dwc2
driver mainline. Is it possible to use that one instead the dwc_otg? It
provides host and device functionality and it should be the same USB
core.

[0] https://wiki.linuxfoundation.org/realtime/documentation/known_limitations

Regards,
Oussama

Sebastian