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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Fri, 9 Jul 2021 00:56:13 +0000
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Subject: Re: [PATCH V3 1/3] arm64: dts: sc7280: Add QSPI node
To:     Bjorn Andersson <bjorn.andersson@linaro.org>, rojay@codeaurora.org
Cc:     agross@kernel.org, robh+dt@kernel.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Rajendra Nayak <rnayak@codeaurora.org>,
        saiprakash.ranjan@codeaurora.org, msavaliy@qti.qualcomm.com
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Quoting rojay@codeaurora.org (2021-07-06 02:19:27)
> On 2021-06-08 13:37, rojay@codeaurora.org wrote:
> > On 2021-06-06 09:25, Bjorn Andersson wrote:
> >> On Fri 04 Jun 08:54 CDT 2021, Roja Rani Yarubandi wrote:
> >>
> >>> Add QSPI DT node for SC7280 SoC.
> >>>
> >>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
> >>> ---
> >>> Changes in V3:
> >>>  - Broken the huge V2 patch into 3 smaller patches.
> >>>    1. QSPI DT nodes
> >>>    2. QUP wrapper_0 DT nodes
> >>>    3. QUP wrapper_1 DT nodes
> >>>
> >>> Changes in V2:
> >>>  - As per Doug's comments removed pinmux/pinconf subnodes.
> >>>  - As per Doug's comments split of SPI, UART nodes has been done.
> >>>  - Moved QSPI node before aps_smmu as per the order.
> >>>
> >>>  arch/arm64/boot/dts/qcom/sc7280-idp.dts | 29 ++++++++++++
> >>>  arch/arm64/boot/dts/qcom/sc7280.dtsi    | 61
> >>> +++++++++++++++++++++++++
> >>>  2 files changed, 90 insertions(+)
> >>>
> >>> diff --git a/arch/arm64/boot/dts/qcom/sc7280-idp.dts
> >>> b/arch/arm64/boot/dts/qcom/sc7280-idp.dts
> >>> index 3900cfc09562..d0edffc15736 100644
> >>> --- a/arch/arm64/boot/dts/qcom/sc7280-idp.dts
> >>> +++ b/arch/arm64/boot/dts/qcom/sc7280-idp.dts
> >>> @@ -268,6 +268,22 @@ pmr735b_die_temp {
> >>>             };
> >>>  };
> >>>
> >>> +&qspi {
> >>> +   status = "okay";
> >>> +   pinctrl-names = "default";
> >>> +   pinctrl-0 = <&qspi_clk>, <&qspi_cs0>, <&qspi_data01>;
> >>> +
> >>> +   flash@0 {
> >>> +           compatible = "jedec,spi-nor";
> >>> +           reg = <0>;
> >>> +
> >>> +           /* TODO: Increase frequency after testing */
> >>> +           spi-max-frequency = <25000000>;
> >>> +           spi-tx-bus-width = <2>;
> >>> +           spi-rx-bus-width = <2>;
> >>> +   };
> >>> +};
> >>> +
> >>>  &qupv3_id_0 {
> >>>     status = "okay";
> >>>  };
> >>> @@ -278,6 +294,19 @@ &uart5 {
> >>>
> >>>  /* PINCTRL - additions to nodes defined in sc7280.dtsi */
> >>>
> >>> +&qspi_cs0 {
> >>> +   bias-disable;
> >>> +};
> >>> +
> >>> +&qspi_clk {
> >>> +   bias-disable;
> >>> +};
> >>> +
> >>> +&qspi_data01 {
> >>> +   /* High-Z when no transfers; nice to park the lines */
> >>> +   bias-pull-up;
> >>> +};
> >>> +
> >>>  &qup_uart5_default {
> >>>     tx {
> >>>             pins = "gpio46";
> >>> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> >>> b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> >>> index 6c9d5eb93f93..3047ab802cd2 100644
> >>> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> >>> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> >>> @@ -1061,6 +1061,42 @@ apss_merge_funnel_in: endpoint {
> >>>                     };
> >>>             };
> >>>
> >>> +           qspi_opp_table: qspi-opp-table {
> >>
> >> This node doesn't represents anything on the mmio bus, so it shouldn't
> >> live in in /soc. Can't you move it into &qspi?
> >>
> >> Regards,
> >> Bjorn
> >>
> >
> > Sure, will move it into qspi node.
> >
> > Thanks,
> > Roja
> >
>
> Hi Bjorn,
>
> Moving "qspi_opp_table" inside &qspi node causing this warning:
> arch/arm64/boot/dts/qcom/sc7280.dtsi:1055.35-1072.6: Warning
> (spi_bus_reg): /soc@0/spi@88dc000/qspi-opp-table: missing or empty reg
> property

If DT folks are OK I think we should hard-code 'opp-table' as not a
device for spi to populate on the spi bus and relax the warning in the
devicetree compiler (see [1] for more details). Technically, nodes that
are bus controllers assume all child nodes are devices on that bus.  In
this case, we want to stick the opp table as a child of the spi node so
that it can be called 'opp-table' and not be a node in the root of DT.

>
> Shall I keep the qspi-opp-table out of &qspi node?
>

If you do, please move it to / instead of putting it under /soc as it
doesn't have an address or a reg property.

[1] https://github.com/dgibson/dtc/blob/69595a167f06c4482ce784e30df1ac9b16ceb5b0/checks.c#L1844