linux-kernel - Re: [PATCH RESEND v2] dt-bindings: pwm: mediatek: Add compatible for MT7986

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Message-ID: <375d45fa-fdfc-37a5-9d32-b0412cad7bc0@collabora.com>
Date:   Fri, 25 Nov 2022 12:12:17 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Daniel Golle <daniel@...rotopia.org>,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pwm@...r.kernel.or,
        Matthias Brugger <matthias.bgg@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Thierry Reding <thierry.reding@...il.com>
Cc:     Fabien Parent <fparent@...libre.com>,
        Zhi Mao <zhi.mao@...iatek.com>,
        Sam Shih <sam.shih@...iatek.com>
Subject: Re: [PATCH RESEND v2] dt-bindings: pwm: mediatek: Add compatible for
 MT7986

Il 24/11/22 12:03, Daniel Golle ha scritto:
> Add new compatible string for MT7986 PWM and list compatible units for
> existing entries. Also make sure the number of pwm1-X clocks is listed
> for all supported units.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
> Changes since v1: list compatibles, fix pwm1-n clocks for all SoCs
> 
> Rebased on linux-next and re-run scripts/get_maintainers.pl on patch to
> makes sure dt maintainers are included. This has been requested by
> Krzysztof Kozlowski.
> 
>   .../devicetree/bindings/pwm/pwm-mediatek.txt  | 20 +++++++++++--------
>   1 file changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> index 554c96b6d0c3..952a338e06e7 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> @@ -2,14 +2,15 @@ MediaTek PWM controller
>   
>   Required properties:
>    - compatible: should be "mediatek,<name>-pwm":
> -   - "mediatek,mt2712-pwm": found on mt2712 SoC.
> +   - "mediatek,mt2712-pwm", "mediatek,mt6795-pwm": found on mt2712 SoC.
>      - "mediatek,mt6795-pwm": found on mt6795 SoC.
> -   - "mediatek,mt7622-pwm": found on mt7622 SoC.
> -   - "mediatek,mt7623-pwm": found on mt7623 SoC.
> +   - "mediatek,mt7622-pwm", "mediatek,mt8195-pwm", "mediatek,mt8183-pwm", "mediatek,mt7986-pwm": found on mt7622 SoC.
> +   - "mediatek,mt7623-pwm", "mediatek,mt7628-pwm": found on mt7623 SoC.
>      - "mediatek,mt7628-pwm": found on mt7628 SoC.
>      - "mediatek,mt7629-pwm": found on mt7629 SoC.
> -   - "mediatek,mt8183-pwm": found on mt8183 SoC.
> -   - "mediatek,mt8195-pwm", "mediatek,mt8183-pwm": found on mt8195 SoC.
> +   - "mediatek,mt7986-pwm": found on mt7986 SoC.
> +   - "mediatek,mt8183-pwm", "mediatek,mt7986-pwm": found on mt8183 SoC.
> +   - "mediatek,mt8195-pwm", "mediatek,mt8183-pwm", "mediatek,mt7986-pwm": found on mt8195 SoC.

I'm sorry, but all these compatibles make little sense at best.
Each of these PWM controllers have different properties as they may *by hardware*
be featuring more or less channels, they may be a different IP revision and/or
sub-revision requiring even ever-so-slightly different handling (check pwm45_fixup
and has_ck_26m_sel).

If you want to add MT7986, the best thing that you can do is to simply add

+   - "mediatek,mt7986-pwm": found on mt7986 SoC.

this line ^

...and then please don't touch the others.

>      - "mediatek,mt8365-pwm": found on mt8365 SoC.
>      - "mediatek,mt8516-pwm": found on mt8516 SoC.
>    - reg: physical base address and length of the controller's registers.
> @@ -20,11 +21,14 @@ Required properties:
>                   has no clocks
>      - "top": the top clock generator
>      - "main": clock used by the PWM core
> +   - "pwm1"  : the PWM1 clock for mt7629
> +   - "pwm1-2": the two per PWM clocks for mt7986

That's not your fault, but the binding is already wrong (yes it must be fixed!) and
unless my brain is failing somewhere, there's only one clock per pwm (as if there's
any children, it must be parented to .. well, its parent, in the clock driver), and
note that the driver is actually parsing "pwmX" clocks, never "pwmX-Y" clocks.

Relevant snippet:

		char name[8];

		snprintf(name, sizeof(name), "pwm%d", i + 1);

		pc->clk_pwms[i] = devm_clk_get(&pdev->dev, name);

Just... please don't keep doing the same mistake that is already inside of here...

So, coming to an end: I think that this commit should be a one-liner that documents
your "mediatek,mt7986-pwm" compatible and that's it.

A schema conversion would be welcome: in that regard, I can make a conversion
and send it next week, along with that clock-names fix.

Regards,
Angelo