Re: [PATCH 1/2] dt-bindings: arm: qcom: document zoglin board

From: Rob Herring <robh@kernel.org>
To: Doug Anderson <dianders@chromium.org>
Cc: Bob Moragues <moragues@chromium.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Bob Moragues <moragues@google.com>,
	Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Stephen Boyd <sboyd@codeaurora.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>
Subject: Re: [PATCH 1/2] dt-bindings: arm: qcom: document zoglin board
Date: Wed, 27 Jul 2022 13:43:20 -0600	[thread overview]
Message-ID: <CAL_JsqJ=jj6isKbBEKGjax266MS_h+Oehn9zYMMjXzc3K-t4Wg@mail.gmail.com> (raw)
In-Reply-To: <CAD=FV=U8ek0FR=hZwemK5JcbUP=JsnRTtv7WzJKmOb-UFwHfXA@mail.gmail.com>

On Wed, Jul 27, 2022 at 11:40 AM Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Wed, Jul 27, 2022 at 9:03 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Tue, Jul 26, 2022 at 09:24:31PM -0700, Bob Moragues wrote:
> > > Zoglin is a Hoglin Chromebook with SPI Flash reduced from 64MB to 8MB.
> > > Zoglin is identical to Hoglin except for the SPI Flash.
> > > The actual SPI Flash is dynamically probed at and not specified in DTS.
> > >
> > > Signed-off-by: Bob Moragues <moragues@chromium.org>
> > >
> > > Signed-off-by: Bob Moragues <moragues@google.com>
> > > ---
> > >
> > >  Documentation/devicetree/bindings/arm/qcom.yaml | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml b/Documentation/devicetree/bindings/arm/qcom.yaml
> > > index 581485392404..63091df3cbb3 100644
> > > --- a/Documentation/devicetree/bindings/arm/qcom.yaml
> > > +++ b/Documentation/devicetree/bindings/arm/qcom.yaml
> > > @@ -475,6 +475,7 @@ properties:
> > >
> > >        - description: Qualcomm Technologies, Inc. sc7280 CRD platform (newest rev)
> > >          items:
> > > +          - const: google,zoglin
> > >            - const: google,hoglin
> > >            - const: qcom,sc7280
> >
> > Is just "google,hoglin", "qcom,sc7280" no longer valid? If it is valid,
> > you need another entry.
>
> If it makes people happy to have another entry then it wouldn't hurt,
> but it has no long term benefit and I would recommend against it. The
> next patch in this series changes the existing "hoglin" device tree to
> have all 3 compatible strings and thus when both patches land then
> make dtbs_check will pass. I assume that is the only goal of
> documenting these boards here. Certainly if you had a device tree that
> had only "google,zoglin" it would boot fine on zoglin devices and if
> you had a device tree that had only "google,hoglin" it would boot fine
> on hoglin device. This is true of all of the entries for Chromebooks
> that have multiple compatible entries.

Why even add the entry? If it is just a different SPI flash, you can
tell that from the SPI flash compatible or device ID.

Rob