DWC OTG TX path optimisation for 11-current

[Andreas Schwarz]

On 25.09.15, Andreas Schwarz wrote:
> On 24.09.15, Svatopluk Kraus wrote:
>
>> I finally found a way how to get something what could be analyzed
>> considering the problem with smcs warnings, slow console response, and
>> other oddities. And it was Michal Meloun who figured out how the
>> problem comes up. He was so enthusiastic and fast that he got me no
>> chance, no chance at all to figure it out myself. ;)) Thanks goes to
>> Bob Prohaska too who pointed me to stress2 which triggers the problem
>> even with all KTR classes compiled in kernel.
>
> This could explain why the legacy BSD scheduler was so stable compared to 
> ULE. I'll patch and start my buildworld loop test (which will take a week
> (10 loops)).

With this patch my RPI2 is stable like hell. I've completed 10 buildworld
runs (with -4) in series, without any issues. Please commit, if not done yet.


root at pizelot:~ # uname -a
FreeBSD pizelot.schwarzes.net 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r288200M: Fri Sep 25 08:35:44 CEST 2015
root at pizelot.schwarzes.net:/usr/obj/usr/src/sys/RPI2-B-ASC  arm


-asc