linux-kernel - Re: [PATCH v2 3/3] dt-bindings: arm: msm: Convert kpss-gcc driver Documentation to yaml

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Date:   Mon, 2 May 2022 12:40:04 +0200
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 3/3] dt-bindings: arm: msm: Convert kpss-gcc driver
 Documentation to yaml

On Sun, May 01, 2022 at 10:26:47AM +0200, Krzysztof Kozlowski wrote:
> On 30/04/2022 09:42, Ansuel Smith wrote:
> > On Sat, Apr 30, 2022 at 04:40:54PM +0200, Krzysztof Kozlowski wrote:
> >> On 30/04/2022 08:01, Ansuel Smith wrote:
> >>> Convert kpss-gcc driver Documentation to yaml.
> >>> Add #clock-cells additional binding to required bindings and example
> >>> as it's a required binding for clock-output-names.
> >>>
> >>> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> >>
> >>
> >> (...)
> >>
> >>> +properties:
> >>> +  compatible:
> >>> +    items:
> >>> +      - enum:
> >>> +          - qcom,kpss-gcc-ipq8064
> >>> +          - qcom,kpss-gcc-apq8064
> >>> +          - qcom,kpss-gcc-msm8974
> >>> +          - qcom,kpss-gcc-msm8960
> >>> +      - const: qcom,kpss-gcc
> >>> +
> >>> +  reg:
> >>> +    maxItems: 1
> >>> +
> >>> +  clocks:
> >>> +    items:
> >>> +      - description: phandle to pll8_vote
> >>> +      - description: phandle to pxo_board
> >>> +
> >>> +  clock-names:
> >>> +    items:
> >>> +      - const: pll8_vote
> >>> +      - const: pxo
> >>> +
> >>> +  clock-output-names:
> >>> +    const: acpu_l2_aux
> >>
> >> It does not make sense having a constant output name. What is the
> >> meaning this property in such case? The original binding did not enforce it.
> >>
> >>
> >>
> >> Best regards,
> >> Krzysztof
> > 
> > Mh. Should I just drop the const and put a description referring to an
> > advised name? The driver with the kpss-gcc hardcode the name to
> > acpu_l2_aux that's why I thought it was a correct conversion using a
> > const but I assume this is another problem of not making a correct 1:1
> > conversion and adding fixes on pure conversion.
> 
> Hard-coding a name by implementation is not a reason to put that name in
> DTS. DTS is not a place for values stored in the driver.
> 
> > Think I should drop it and put a description to it. (and then later fix
> > it when I will push the other series with all the tweaks)
> 
> The driver kpss-gcc does not use this property at all, so I am not sure
> if there is a point to even keep it. Any other user of bindings makes
> use of the property?
> 
> 
> Best regards,
> Krzysztof

The idea is that you put the clk name in 'clock-output-names' and the
driver needs to have support for it (and set the clk name based on the
name defined in the dts)

This driver doesn't have support for it and is actually hardcoded.
So you are right and I should just drop it.

But now another question... Since #clock-cells was added as a
requirement for clock-output-names, should I drop also that?

In theory #clock-cells should always be declared for clock providers, is
it right to add it in the conversion commit or I should put this change
in another commit? (since it's now an addition and now something required
to fix a bot warning)

-- 
	Ansuel