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Date:   Mon, 27 Mar 2023 17:02:59 +0300
From:   Dmitry Rokosov <ddrokosov@sberdevices.ru>
To:     <neil.armstrong@linaro.org>
CC:     <mturquette@baylibre.com>, <sboyd@kernel.org>,
        <robh+dt@kernel.org>, <krzysztof.kozlowski+dt@linaro.org>,
        <khilman@baylibre.com>, <martin.blumenstingl@googlemail.com>,
        <jian.hu@amlogic.com>, <kernel@sberdevices.ru>,
        <rockosov@gmail.com>, <linux-amlogic@lists.infradead.org>,
        <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v11 3/5] dt-bindings: clock: meson: add A1 PLL and
 Peripherals clkcs bindings
Message-ID: <20230327140259.xtiyoia4f7eir4bm@CAB-WSD-L081021>
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On Mon, Mar 27, 2023 at 03:55:46PM +0200, neil.armstrong@linaro.org wrote:
> On 27/03/2023 15:19, Dmitry Rokosov wrote:
> > On Mon, Mar 27, 2023 at 02:03:25PM +0200, neil.armstrong@linaro.org wrote:
> > > On 27/03/2023 13:39, Jerome Brunet wrote:
> > > > 
> > > > On Mon 27 Mar 2023 at 13:51, Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote:
> > > > 
> > > > > On Mon, Mar 27, 2023 at 11:51:21AM +0200, Jerome Brunet wrote:
> > > > > > 
> > > > > > On Tue 21 Mar 2023 at 22:30, Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote:
> > > > > > 
> > > > > > > Add the documentation for Amlogic A1 PLL and Amlogic A1 Peripherals
> > > > > > > clock drivers.
> > > > > > > Introduce Amlogic A1 PLL and Amlogic A1 Peripherals device tree
> > > > > > > bindings and include them to MAINTAINERS.
> > > > > > > 
> > > > > > > Signed-off-by: Jian Hu <jian.hu@amlogic.com>
> > > > > > > Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
> > > > > > > ---
> > > > > > >    .../bindings/clock/amlogic,a1-clkc.yaml       |  73 +++++++++++
> > > > > > >    .../bindings/clock/amlogic,a1-pll-clkc.yaml   |  59 +++++++++
> > > > > > >    MAINTAINERS                                   |   1 +
> > > > > > >    include/dt-bindings/clock/amlogic,a1-clkc.h   | 113 ++++++++++++++++++
> > > > > > >    .../dt-bindings/clock/amlogic,a1-pll-clkc.h   |  21 ++++
> > > > > > >    5 files changed, 267 insertions(+)
> > > > > > >    create mode 100644 Documentation/devicetree/bindings/clock/amlogic,a1-clkc.yaml
> > > > > > >    create mode 100644 Documentation/devicetree/bindings/clock/amlogic,a1-pll-clkc.yaml
> > > > > > 
> > > > > > There is two drivers (and 2 independent patches). There should be 2
> > > > > > bindings patches as well.
> > > > > > 
> > > > > 
> > > > > Before, in previous versions I had two versions, but it wasn't bisectable
> > > > > approach.
> > > > 
> > > > You are confusing bisectable and Rob's robot. Splitting patches is more
> > > > that likely to help bisect (and patches backport) - not the other way around.
> > > > 
> > > > > a1-clkc schema depends on a1-pll-clkc headers and vice versa.
> > > > > It means dt schemas checkers will show us failure if we split them into two
> > > > > patchsets.
> > > > 
> > > > Only because you are patches are not upstream yet ...
> > > > 
> > > > > I know, that we can use raw digits instead of CLKID names, but IMO it doesn't
> > > > > look like production schema and it requires one more patchset above the
> > > > > series with proper CLKID definitons usage and proper header including.
> > > > > 
> > > > > BTW, there is an example of Rob's test bot failure found in the previous
> > > > > v10 patch series due to chicken or the egg problem.
> > > > > https://lore.kernel.org/all/167769997208.7087.5344356236212731922.robh@kernel.org/
> > > > > 
> > > > > Please advise what's the best practice to resolve that..
> > > > 
> > > > Don't use the header in your example would solve the problem and
> > > > still be correct DT wise.
> > > > 
> > > > The examples are just examples, they are not required to actually
> > > > matches a real HW, as far as I know.
> > > 
> > > Exact, you can use fake lables instead of defined:
> > > 
> > > <&clkc_pll CLKID_FCLK_DIV2>,
> > > 
> > > =>
> > > remove "#include <dt-bindings/clock/amlogic,a1-pll-clkc.h>"
> > > 
> > > <&clkc_pll_fclk_div2>,
> > > 
> > > is perfectly ok and will permit have 2 separate patches.
> > > 
> > > The dependency is only if you have a common yaml file for
> > > both bindings files, but this is not the case here.
> > 
> > Simple removal of "#include <dt-bindings/clock/amlogic,a1-pll-clkc.h>"
> > header doesn't work, dt_binding_check make rule is failed:
> 
> I never wrote you to only remove the include, adding fake labels phandles was the logical next step.

Ah, sorry, I've confused. Anyway, the fake labels are working perfectly.
DT checkers are silent.

> > 
> > Error: Documentation/devicetree/bindings/clock/amlogic,a1-clkc.example.dts:28.37-38 syntax error
> > FATAL ERROR: Unable to parse input tree
> > 
> > It happens, because 'dt_binding_check' generates simple dts example and
> > tries to compile it:
> > 
> > cat Documentation/devicetree/bindings/clock/amlogic,a1-clkc.example.dts
> > ===
> > 
> > /dts-v1/;
> > /plugin/; // silence any missing phandle references
> > 
> > 
> > /{
> >      compatible = "foo";
> >      model = "foo";
> >      #address-cells = <1>;
> >      #size-cells = <1>;
> > 
> > 
> > 
> >      example-0 {
> >          #address-cells = <1>;
> >          #size-cells = <1>;
> > 
> > 
> >          apb {
> >              #address-cells = <2>;
> >              #size-cells = <2>;
> >              clock-controller@800 {
> >                  compatible = "amlogic,a1-clkc";
> >                  reg = <0 0x800 0 0x104>;
> >                  #clock-cells = <1>;
> >                  clocks = <&clkc_pll CLKID_FCLK_DIV2>,
> >                           <&clkc_pll CLKID_FCLK_DIV3>,
> >                           <&clkc_pll CLKID_FCLK_DIV5>,
> >                           <&clkc_pll CLKID_FCLK_DIV7>,
> >                           <&clkc_pll CLKID_HIFI_PLL>,
> >                           <&xtal>;
> >                  clock-names = "fclk_div2", "fclk_div3",
> >                                "fclk_div5", "fclk_div7",
> >                                "hifi_pll", "xtal";
> >              };
> >          };
> > 
> >      };
> > };
> > ===
> > 
> > As you can see, header is required.
> > 
> > But looks like, dt binding checker is happy with the fake references hack :)
> > Below there is generated example dts:
> > 
> > cat Documentation/devicetree/bindings/clock/amlogic,a1-clkc.example.dts
> > ===
> > 
> > /dts-v1/;
> > /plugin/; // silence any missing phandle references
> > 
> > 
> > /{
> >      compatible = "foo";
> >      model = "foo";
> >      #address-cells = <1>;
> >      #size-cells = <1>;
> > 
> > 
> > 
> >      example-0 {
> >          #address-cells = <1>;
> >          #size-cells = <1>;
> > 
> > 
> >          apb {
> >              #address-cells = <2>;
> >              #size-cells = <2>;
> >              clock-controller@800 {
> >                  compatible = "amlogic,a1-clkc";
> >                  reg = <0 0x800 0 0x104>;
> >                  #clock-cells = <1>;
> >                  clocks = <&clkc_pll_fclk_div2>,
> >                           <&clkc_pll_fclk_div3>,
> >                           <&clkc_pll_fclk_div5>,
> >                           <&clkc_pll_fclk_div7>,
> >                           <&clkc_pll_hifi_pll>,
> >                           <&xtal>;
> >                  clock-names = "fclk_div2", "fclk_div3",
> >                                "fclk_div5", "fclk_div7",
> >                                "hifi_pll", "xtal";
> >              };
> >          };
> > 
> >      };
> > };
> > ===
> > 
> > Yep, we are able to cheat dt checkers, but we don't help dt developers
> > with such example.
> > May be, it's better to prepare two patches in such hierarchy:
> > 
> > 1) A1 PLL clkc bindings with fake references without clkc headers
> > 2) A1 clkc bindings with real CLKID bindings + A1 PLL clkc bindings fix
> > with real CLKID A1 clkc bindings + header.
> > 
> > The such approach resolves DT checkers failures and split DT bindings
> > into two patchsets.

What do you think about patchsets form listed above? Fake labels as a
first step and real CLKIDs as a second. I'm embarrassed only that second
patch fixes the previous in the one patch series...

-- 
Thank you,
Dmitry