linux-kernel - Re: [PATCH v1 3/4] ASoC: codecs: pcm179x: Add reset gpio

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Message-ID: <20180301091347.6575e621@dell-desktop.home>
Date:   Thu, 1 Mar 2018 09:13:47 +0100
From:   Mylène Josserand <mylene.josserand@...tlin.com>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        alexandre.belloni@...tlin.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v1 3/4] ASoC: codecs: pcm179x: Add reset gpio

Hello Fabio,

Thank you for the review!

On Tue, 27 Feb 2018 19:30:11 -0300
Fabio Estevam <festevam@...il.com> wrote:

> On Tue, Feb 27, 2018 at 6:24 PM, Mylène Josserand
> <mylene.josserand@...tlin.com> wrote:
> 
> > +       pcm179x->reset = of_get_named_gpio(np, "reset-gpios", 0);
> > +       if (gpio_is_valid(pcm179x->reset)) {
> > +               ret = devm_gpio_request_one(dev, pcm179x->reset,
> > +                                           GPIOF_OUT_INIT_LOW,
> > +                                           "pcm179x reset");
> > +               if (ret) {
> > +                       dev_err(dev,
> > +                               "Failed to request GPIO %d as reset pin, error %d\n",
> > +                               pcm179x->reset, ret);
> > +                       return ret;
> > +               }
> > +
> > +               gpio_set_value(pcm179x->reset, 1);  
> 
> It would be better to use the gpiod API, which takes the GPIO polarity
> into account.
> 
> There may be systems that have an inverter connected to this pin, and
> this can be changed in dts via GPIO_ACTIVE_HIGH.

Oh, true, I should have used gpiod. Thanks for pointing me out.

> 
> Also, as the reset pin can be connected to an I2C expander, for
> example, so it is safer to use the cansleep variant:
> 
> gpiod_set_value_cansleep(pcm179x->reset, 0);

Sure, I will update it.

Thanks,

Mylène

-- 
Mylène Josserand, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com