Date: Tue, 8 Mar 2016 18:49:42 +0100 (CET)
From: Stefan Wahren <stefan.wahren@i2se.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Michael Niewoehner <linux@mniewoehner.de>,
        Tao Huang <huangtao@rock-chips.com>,
        Julius Werner <jwerner@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        John Youn <johnyoun@synopsys.com>,
        Caesar Wang <caesar.upstream@gmail.com>,
        Heiko Stuebner <heiko@sntech.de>, Felipe Balbi <balbi@kernel.org>,
        Remi Pommarel <repk@triplefau.lt>
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Subject: Re: [RFT PATCH 2/2] Revert "usb: dwc2: Fix probe problem on
 bcm2835"
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Hi Doug,

> Doug Anderson <dianders@chromium.org> hat am 7. März 2016 um 22:30
> geschrieben:
>
>
> Stefan,
>
> On Mon, Mar 7, 2016 at 10:40 AM, Stefan Wahren <stefan.wahren@i2se.com> wrote:
> > Hi Doug,
> >
> >> Douglas Anderson <dianders@chromium.org> hat am 4. März 2016 um 19:23
> >> geschrieben:
> >>
> >>
> >> This reverts commit 192cb07f7928 ("usb: dwc2: Fix probe problem on
> >> bcm2835") now that we've found the root cause. See the change
> >> titled ("usb: dwc2: Add a 10 ms delay to dwc2_core_reset()").
> >
> > adding a delay of 10 ms after a core reset might be a idea, but applying
> > both
> > patches breaks USB support on RPi :-(
> >
> > I'm getting the wrong register values ...
>
> Ugh. :(
>
> Just out of curiosity, if you loop and time long it takes for the
> registers to get to the right state after reset, what do you get?
> AKA, pick:
>
> https://chromium-review.googlesource.com/331260
>
> ...and let me know what it prints out. On my system I see:
>
> [ 1.990743] dwc2 ff540000.usb: Waited 300001 us, 0x04000400 =>
> 0x04000400, 0x02000800 => 0x02000800
> [ 2.119677] dwc2 ff580000.usb: Waited 9997 us, 0x00100400 =>
> 0x04000400, 0x00000000 => 0x02000800

sure, but this will take some time (weekend).

>
> I believe the difference in behavior is because of the two different
> types of USB controllers (one is OTG and the other is host only).
>
>
> -Doug