Re: [RFCv1 1/3] phy: meson8b-usb2: Enable otg phy controller on Meson8b SoCs

From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Anand Moon <linux.amoon@gmail.com>
Cc: devicetree <devicetree@vger.kernel.org>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Rob Herring <robh+dt@kernel.org>,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [RFCv1 1/3] phy: meson8b-usb2: Enable otg phy controller on Meson8b SoCs
Date: Wed, 6 Feb 2019 12:48:40 +0100	[thread overview]
Message-ID: <CAFBinCAhjo4ueh6UDE+TKiF8Vc2Pz2JsjzcVsrsPQMU=ZEiLwQ@mail.gmail.com> (raw)
In-Reply-To: <CANAwSgSh--pom9kmVBWejHwVHJNv2o4Ta93wabR3Ak=f3V4JbQ@mail.gmail.com>

Hi Anand,

On Tue, Feb 5, 2019 at 8:52 PM Anand Moon <linux.amoon@gmail.com> wrote:
[...]
> > personally I would start with getting device / peripheral mode working for usb0.
> > if you're lucky the PHY driver will work without any changes and you
> > only need to set the correct dr_mode along with the g-* properties.
> >
>
> Yes that should be the goal on getting working usb0 phy and otg port.
> So for now we will drop this patch and disable the usb_phy0 mode in
> dts for Odroid c2
> in order to get ride of the power failed WARNING.
I checked Kevin's Odroid-C2 (GXBB) on Kernel CI and I can't see any
power failed warning: [0]

> When we get the usb0 node to work again with good phy configuration and
> tuning we can re-enable the nodes. I will try to look into this in the future.
>
> Can you share your thought on this.
sounds good to me! especially because it would give us OTG support on
Meson8, Meson8b, Meson8m2 and GXBB (because these SoCs are sharing the
same USB implementation)!

I see four challenges:
1. getting host mode working on the micro USB port. you have already
proven that you can do this :)
2. getting peripheral mode working on the micro USB port. my hope is
that it's only about setting the right dr_mode and the g-* properties
on the usb0 node (but I haven't tried this)
3. make OTG detection work and integrate it with dwc2. I would consult
the dwc2 maintainers to see what can be done
4. bring everything together, making sure that one feature doesn't break another

Regards
Martin

[0] https://storage.kernelci.org/next/master/next-20190130/arm64/defconfig/lab-baylibre-seattle/boot-meson-gxbb-odroidc2.html

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