linux-kernel - Re: [PATCH v1 1/5] docs: firmware-guide: ACPI: Add a PWM example

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Message-ID: <YLUKKeltfJe+4X2k@smile.fi.intel.com>
Date:   Mon, 31 May 2021 19:09:13 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Flavio Suligoi <f.suligoi@...m.it>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pwm@...r.kernel.org
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH v1 1/5] docs: firmware-guide: ACPI: Add a PWM example

On Mon, May 31, 2021 at 06:43:47PM +0300, Andy Shevchenko wrote:
> When PWM support for ACPI has been added into the kernel, it missed
> the documentation update. Hence update documentation here.

I am actually in doubt that original commit message provides that short period
intentionally. Possibly it was misinterpretation of nanoseconds (which is
expected by PWM framework) with microseconds than might sound logical for LED.

Perhaps we may add 000 to the value (1) and replace us by ms in the text (2).

...

> +                    Package () {
> +                        "\\_SB.PCI0.PWM",  // <PWM device reference>
> +                        0,                 // <PWM index>

> +                        600000,            // <PWM period>

(1)

> +                        0,                 // <PWM flags>
> +                    }

> +In the above example the PWM-based LED driver references to the PWM channel 0
> +of \_SB.PCI0.PWM device with initial period setting equal to 600 us (note that

(2)

> +value is given in nanoseconds).

-- 
With Best Regards,
Andy Shevchenko