linux-kernel - Re: [PATCH 18/48] ARM: pxa: hx4700: use gpio descriptors for audio

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Date:   Wed, 4 May 2022 23:59:30 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Robert Jarzmik <robert.jarzmik@...e.fr>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>, Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Philipp Zabel <philipp.zabel@...il.com>,
        Lubomir Rintel <lkundrak@...sk>,
        Paul Parsons <lost.distance@...oo.com>,
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        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
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Subject: Re: [PATCH 18/48] ARM: pxa: hx4700: use gpio descriptors for audio

On Mon, May 2, 2022 at 9:08 AM Arnd Bergmann <arnd@...nel.org> wrote:
> On Sun, May 1, 2022 at 11:41 PM Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > (...)
> > > +static struct gpiod_lookup_table hx4700_audio_gpio_table = {
> > > +       .dev_id = "hx4700-audio",
> > > +       .table = {
> > > +               GPIO_LOOKUP("gpio-pxa", GPIO75_HX4700_EARPHONE_nDET,
> > > +                           "earphone-ndet", GPIO_ACTIVE_HIGH),
> >
> > This looks wrong. The n in nDET in the end of the name of the GPIO line
> > means active low does it not?
> >
> > What I usually do when I see this is to properly set it to
> > GPIO_ACTIVE_LOW in the descriptor table, then invert the logic
> > where it's getting used.
> >
> > Also rename to earphone-det instead of -ndet
>
> Thanks for taking a look! I changed it now, but I don't know if
> I got the correct number of inversions in the end. How does this look?

Looks wrong, you can just invert the argument to any statement of set_value()
after tagging respective line as active low. Then gpilob will do a second
inversion.

> +               GPIO_LOOKUP("gpio-pxa", GPIO75_HX4700_EARPHONE_nDET,
> +                           "earphone-det", GPIO_ACTIVE_LOW),
> +               GPIO_LOOKUP("gpio-pxa", GPIO107_HX4700_SPK_nSD,
> +                           "spk-sd", GPIO_ACTIVE_LOW),

So those two have switched polarity.

> @@ -81,14 +79,14 @@ static const struct snd_soc_ops hx4700_ops = {
>  static int hx4700_spk_power(struct snd_soc_dapm_widget *w,
>                             struct snd_kcontrol *k, int event)
>  {
> -       gpio_set_value(GPIO107_HX4700_SPK_nSD, !!SND_SOC_DAPM_EVENT_ON(event));
> +       gpiod_set_value(gpiod_spk_sd, !!SND_SOC_DAPM_EVENT_ON(event));

Thus drop one ! in front of the expression, just !SND_SOC_DAPM_EVENT_ON(event)

> -       gpio_set_value(GPIO92_HX4700_HP_DRIVER, !!SND_SOC_DAPM_EVENT_ON(event));
> +       gpiod_set_value(gpiod_hp_driver, !!SND_SOC_DAPM_EVENT_ON(event));

But not this.

> +       gpiod_spk_sd = devm_gpiod_get(&pdev->dev, "spk-sd", GPIOD_OUT_LOW);

These initial values don't seem to be set in the old code you could
just use GPIOD_ASIS as flag to make sure the new code behaves
the same.

Yours,
Linus Walleij