linux-kernel - Re: [PATCH v9 0/2] PWM support for HiFive Unleashed

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Date:   Tue, 19 Mar 2019 11:56:35 +0530
From:   Yash Shah <yash.shah@...ive.com>
To:     Andreas Schwab <schwab@...e.de>
Cc:     Palmer Dabbelt <palmer@...ive.com>, linux-pwm@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Thierry Reding <thierry.reding@...il.com>, robh+dt@...nel.org,
        mark.rutland@....com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sachin Ghadi <sachin.ghadi@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Subject: Re: [PATCH v9 0/2] PWM support for HiFive Unleashed

On Mon, Mar 18, 2019 at 10:56 PM Andreas Schwab <schwab@...e.de> wrote:
>
> On Mär 15 2019, Yash Shah <yash.shah@...ive.com> wrote:
>
> > You need to make sure the period setting is passed via the
> > conventional way in DT file.
> > Example:
> > pwmleds {
> >     compatible = "pwm-leds";
> >     heartbeat {
> >         pwms = <&L45 0 10000000 0>;
> >         max-brightness = <255>;
> >         linux,default-trigger = "heartbeat";
> >     };
> > };
>
> I've now managed to build a working FSBL with that change, but that
> didn't change anything.  There is not even a heartbeat option in
> /sys/class/leds/heartbeat/trigger any more.

Below is the copy of the pwm nodes in my DTS file:

L45: pwm@...20000 {
        compatible = "sifive,pwm0";
        interrupt-parent = <&plic0>;
        interrupts = <42 43 44 45>;
        reg = <0x0 0x10020000 0x0 0x1000>;
        reg-names = "control";
        clocks = <&prci 3>;
        #pwm-cells = <2>;
};
L46: pwm@...21000 {
        compatible = "sifive,pwm0";
        interrupt-parent = <&plic0>;
        interrupts = <46 47 48 49>;
        reg = <0x0 0x10021000 0x0 0x1000>;
        reg-names = "control";
        clocks = <&prci 3>;
        #pwm-cells = <2>;
};
pwmleds {
        compatible = "pwm-leds";
        heartbeat {
                pwms = <&L45 0 10000000 0>;
                max-brightness = <255>;
                linux,default-trigger = "heartbeat";
        };
};

The above works for me.
I just noticed that I have been using pwm-cells = 2, instead of 3.
Maybe that is the problem here.
I will suggest you test it on v11 patch in which I will fix this
pwm-cells issue.

Thanks for pointing it out.

>
> Andreas.
>
> --
> Andreas Schwab, SUSE Labs, schwab@...e.de
> GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
> "And now for something completely different."