[LEDE-DEV] [PATCH 3/3] lantiq: add device tree binding for dwc2 on danube

[Ben Mulvihill]

On Sun, 2016-10-30 at 12:27 +0200, Antti Seppälä wrote:
> On 29 October 2016 at 18:31, Ben Mulvihill <ben.mulvihill at gmail.com> wrote:
> > On Sat, 2016-10-29 at 13:28 +0200, Ben Mulvihill wrote:
> >> On Fri, 2016-10-28 at 23:35 +0200, Ben Mulvihill wrote:
> >> > On Fri, 2016-10-28 at 19:14 +0300, Antti Seppälä wrote:
> >> > > On 28 October 2016 at 17:30, Ben Mulvihill <ben.mulvihill at gmail.com> wrote:
> >> > > > Add device tree binding for dwc2 usb driver on lantiq danube
> >> > > >
> >> > > > Signed-off-by: Ben Mulvihill <ben.mulvihill at gmail.com>
> >> > > > ---
> >> > > > diff -uprN a/target/linux/lantiq/dts/danube.dtsi b/target/linux/lantiq/dts/danube.dtsi
> >> > > > --- a/target/linux/lantiq/dts/danube.dtsi       2016-10-27 19:56:07.090392399 +0200
> >> > > > +++ b/target/linux/lantiq/dts/danube.dtsi       2016-10-27 20:47:34.387511522 +0200
> >> > > > @@ -140,7 +140,7 @@
> >> > > >                 };
> >> > > >
> >> > > >                 ifxhcd at E101000 {
> >> > > > -                       compatible = "lantiq,ifxhcd-danube";
> >> > > > +                       compatible = "lantiq,ifxhcd-danube", "lantiq,ifxhcd-danube-dwc2";
> >> > > >                         reg = <0xE101000 0x1000
> >> > > >                                 0xE120000 0x3f000>;
> >> > > >                         interrupt-parent = <&icu0>;
> >> > > >
> >> > > >
> >> > >
> >> > > Hi.
> >> > >
> >> > > Have you tried if danube can simply be compatible with vanilla "snps,dwc2"?
> >> > >
> >> > > The main reason we created our own definition for lantiq is that arx
> >> > > and xrx have fifo sizes smaller than what the dwc2 autodetection
> >> > > mechanism expects.
> >> > > I remember finding some references in ifxhcd code which would suggest
> >> > > that danube had bigger fifo and thus would maybe work without any
> >> > > special treatment.
> >> > >
> >> > > Br,
> >> >
> >> > I'm pretty sure I tried it, but must have been a couple of years
> >> > ago and I can't remember why it didn't work. I'll have another go.
> >> >
> >> > Thanks for the suggestion,
> >> >
> >> > Ben
> >>
> >> You are right. It works fine with "snps,dwc2". (Apart from the same
> >> mode mismatch warnings) When I tried that before I didn't have the
> >> benefit of your hardware initialisation code and my own version
> >> must have been wrong.
> >>
> >> I'll submit a version 2 patch set.
> >>
> >> Ben
> >
> > No, sorry. I was testing the wrong build. I'm afraid "snps,dwc2" doesn't
> > work after all. It tries to autodetect the parameters, doesn't log any
> > errors, but then doesn't recognise devices which are plugged in,
> > so presumably the parameter values it thinks it has detected are
> > not correct.
> >
> > What do you think would be the best thing to do, stick with my original
> > patch set using the same parameters as for arx and vrx, which appear
> > to work fine, or investigate the ifxhcd code and add a separate
> > dwc2_core_params structure called params_danube with (possibly) bigger
> > fifos? I'd prefer the former for simplicity's sake.
> >
> 
> Could you make another simple test where you temporarily edit the
> params_ltq structure to have default values (-1) for all other fields
> than the .otg_cap that is set to 2? The .otg_cap is used to disable
> OTG power and session negotiation that seems to be required for some
> boards.
> 
> The fact that the driver doesn't complain anything about fifo
> initialization suggests that the autodetection is working and reason
> for non-working usb traffic could be elsewhere. However it is possible
> that the autodetection logic is flawed and we need indeed to
> initialize fifos with hard-coded values in which case values from
> params_ltq are probably "good enough".
> 

Yes, setting -1 for all parameters apart from .otg_cap does works.
Does that definitely not work on arx and vrx?

You were right incidentally that the defaults for danube in
ifxhcd are different from the other two. I found:

danube (host mode):
      #define default_param_rx_fifo_size        640
      #define default_param_nperio_tx_fifo_size 640
      #define default_param_perio_tx_fifo_size  768

arx and vrx (host mode):
      #define default_param_rx_fifo_size        240
      #define default_param_nperio_tx_fifo_size 240
      #define default_param_perio_tx_fifo_size  32


Ben