Re: [RFT PATCH 2/2] Revert "usb: dwc2: Fix probe problem on bcm2835"

[Stefan Wahren]

Hi,

> Martin Sperl <kernel@xxxxxxxxxxxxxxxx> hat am 19. MÃrz 2016 um 08:44
> geschrieben:
>
>
>
> > On 19.03.2016, at 03:17, Eric Anholt <eric@xxxxxxxxxx> wrote:
> >
> > Stefan Wahren <stefan.wahren@xxxxxxxx> writes:
> >
> >> Hi Eric,
> >> hi Martin,
> >>
> >>> John Youn <John.Youn@xxxxxxxxxxxx> hat am 16. MÃrz 2016 um 19:28
> >>> geschrieben:
> >>>
> >>>
> >>> On 3/10/2016 11:14 AM, John Youn wrote:
> >>>> On 3/9/2016 11:06 AM, Doug Anderson wrote:
> >>>>>
> >>>>> John: it's pretty clear that there's something taking almost exactly
> >>>>> 10ms on my system and almost exactly 50ms on Stefan's system. Is
> >>>>> there some register we could poll to see when this process is done?
> >>>>> ...or can we look at the dwc2 revision number / feature register and
> >>>>> detect how long to delay?
> >>>>>
>
> Maybe this difference is related to overclocking settings in the firmware?
>
> >>>
> >>> 1. What is the AHB Clock frequency? Is the AHB Clock gated during
> >>> Reset?
> >
> > Low confidence here as I'm tracing lines across a ton of modules, but it
> > looks like it comes from the USB AXI clock in peri_image, which is a
> > gate on the normal 250Mhz APB clock, but nothing should be touching that
> > gate register as part of USB reset as far as I know.
> >
> Isnât it possible that this clock (probably BCM2835_CLOCK_VPU) is
> changed by the firmware due to overclocking settings in /boot/config.txt?

i don't use any overclocking settings. 

Are you able to reproduce the behavior on your Pi?

Stefan

>
> Martin
>
>