linux-kernel - Re: [v6 1/4] dt-bindings: pwm: Add ASPEED PWM Control documentation

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Message-ID: <5b5ccfb9-d6ea-9f22-bc8f-c048da726cc9@linaro.org>
Date:   Thu, 8 Jun 2023 11:27:46 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Billy Tsai <billy_tsai@...eedtech.com>,
        "jdelvare@...e.com" <jdelvare@...e.com>,
        "linux@...ck-us.net" <linux@...ck-us.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "joel@....id.au" <joel@....id.au>,
        "andrew@...id.au" <andrew@...id.au>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "corbet@....net" <corbet@....net>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "patrick@...cx.xyz" <patrick@...cx.xyz>
Subject: Re: [v6 1/4] dt-bindings: pwm: Add ASPEED PWM Control documentation

On 08/06/2023 11:15, Billy Tsai wrote:
> On 08/06/2023 10:21, Billy Tsai wrote:
>         >>         On 08/06/2023 09:47, Billy Tsai wrote:
>         >>         >>
>         >>         >>   >> +
>         >>         >>   >> +allOf:
>         >>         >>   >> +  - $ref: pwm.yaml#
>         >>         >>   >> +
>         >>         >>   >> +properties:
>         >>         >>   >> +  compatible:
>         >>         >>   >> +    enum:
>         >>         >>   >> +      - aspeed,ast2600-pwm
>         >>         >>   >> +
>         >>         >>   >> +  "#pwm-cells":
>         >>         >>   >> +    const: 3
>         >>         >>
>         >>         >>   > 3 cells? For one PWM? What are they?
>         >>         >>
>         >>         >> channel, period and polarity.
>         >>
>         >>         > Don't cut my responses. You wrote you have one PWM output, so only one
>         >>         > channel. What do you put then in the channel?
>         >>
>         >> You need to put 0 in the cell of the channel, the example of the dts usage will like following:
>         >>
>         >> pwm0: pwm0@...10000 {
>         >>         compatible = "aspeed,ast2600-pwm";
>         >>         reg = <0x1e610000 0x8>;
>         >>         #pwm-cells = <3>;
>         >>         #address-cells = <1>;
>         >>         #size-cells = <0>;
>         >>         pinctrl-names = "default";
>         >>         pinctrl-0 = <&pinctrl_pwm0_default>;
>         >>         clocks = <&syscon ASPEED_CLK_AHB>;
>         >>         resets = <&syscon ASPEED_RESET_PWM>;
>         >>         status = "okay";
>         >> };
>         >>
>         >> pwm1: pwm1@...10010 {
>         >>         compatible = "aspeed,ast2600-pwm";
>         >>         reg = <0x1e610010 0x8>;
>         >>         #pwm-cells = <3>;
>         >>         #address-cells = <1>;
>         >>         #size-cells = <0>;
>         >>         pinctrl-names = "default";
>         >>         pinctrl-0 = <&pinctrl_pwm1_default>;
>         >>         clocks = <&syscon ASPEED_CLK_AHB>;
>         >>         resets = <&syscon ASPEED_RESET_PWM>;
>         >>         status = "okay";
> 
>         > BTW, these are not two PWM devices but one. I don't understand why you
>         > changed previous design into something like this, but this is not
>         > representing your hardware.
> 
> The previous design of my patch treated our PWM controller as having 16 PWM channels.
> However, from a hardware perspective, it consists of 16 individual PWM chips, each
> with its own set of two 4-byte control registers. These chips operate independently
> and are not affected by each other.

They are affected by each other - you use the same clock and reset line.
I really doubt you have 16 PWM controllers. Anyway, I cannot judge.
Either your previous submissions were totally bogus or this one is.

Best regards,
Krzysztof