linux-kernel - Re: [RFT PATCH v2 1/2] arm64: dts: qcom: sdm845-db845c: drop unneeded qup_spi0

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Message-ID: <CAD=FV=VCJA0v-EpT9YyCRZg07QzGeH9PGcNcO=j=x0e9XeHtHQ@mail.gmail.com>
Date:   Fri, 2 Dec 2022 06:38:12 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFT PATCH v2 1/2] arm64: dts: qcom: sdm845-db845c: drop unneeded qup_spi0_default

Hi,

On Fri, Dec 2, 2022 at 12:17 AM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
>
> On 02/12/2022 01:49, Doug Anderson wrote:
> > Hi,
> >
> > On Fri, Nov 18, 2022 at 8:42 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski@...aro.org> wrote:
> >>
> >> The qup_spi0_default pin override is exactly the same as one already in
> >> sdm845.dtsi.
> >>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >>
> >> ---
> >>
> >> Cc: Doug Anderson <dianders@...omium.org>
> >>
> >> Changes since v1:
> >> 1. New patch.
> >> ---
> >>  arch/arm64/boot/dts/qcom/sdm845-db845c.dts | 8 --------
> >>  1 file changed, 8 deletions(-)
> >>
> >> diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >> index 02dcf75c0745..56a7afb697ed 100644
> >> --- a/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >> +++ b/arch/arm64/boot/dts/qcom/sdm845-db845c.dts
> >> @@ -1274,11 +1274,3 @@ ov7251_ep: endpoint {
> >>                 };
> >>         };
> >>  };
> >> -
> >> -/* PINCTRL - additions to nodes defined in sdm845.dtsi */
> >> -&qup_spi0_default {
> >> -       config {
> >> -               drive-strength = <6>;
> >> -               bias-disable;
> >> -       };
> >> -};
> >
> > I guess it's more of a question for what Bjorn thinks, but I view the
> > fact that the drive-strength / bias are in the dtsi file to begin with
> > as more as a bug in commit 8f6e20adaaf3 ("arm64: dts: qcom: sdm845:
> > enable dma for spi"), which is where these properties were introduced
> > to sdm845.dtsi.
> >
> > The historical guidance from Bjorn was that things like
> > "drive-strength" and "bias" didn't belong in the SoC dtsi file. Later
> > we came to an agreement that it could be OK to put drive-strength in
> > the SoC dtsi file but that bias was still problematic because it meant
> > ugly "/delete-property/" stuff in the board dtsi files [1].
>
> So let's move it from DTSI to all boards? Although what if the board
> does not use SPI0?

You'd look for boards that set spi0's status to "okay" and those
boards would be the ones to have it in their dtsi.

-Doug