linux-kernel - Re: [v1 2/3] media: ov8856: Add devicetree support

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Date:   Tue, 10 Mar 2020 16:46:56 +0100
From:   Robert Foss <robert.foss@...aro.org>
To:     Fabio Estevam <festevam@...il.com>
Cc:     ben.kao@...el.com, Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan.Cameron@...wei.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-media <linux-media@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-mediatek@...ts.infradead.org,
        Dongchun Zhu <dongchun.zhu@...iatek.com>,
        Tomasz Figa <tfiga@...omium.org>
Subject: Re: [v1 2/3] media: ov8856: Add devicetree support

On Tue, 10 Mar 2020 at 15:03, Fabio Estevam <festevam@...il.com> wrote:
>
> On Tue, Mar 10, 2020 at 10:47 AM Robert Foss <robert.foss@...aro.org> wrote:
>
> > +static int __ov8856_power_on(struct ov8856 *ov8856)
> > +{
> > +       struct i2c_client *client = v4l2_get_subdevdata(&ov8856->sd);
> > +       int ret;
> > +
> > +       ret = clk_prepare_enable(ov8856->xvclk);
> > +       if (ret < 0) {
> > +               dev_err(&client->dev, "failed to enable xvclk\n");
> > +               return ret;
> > +       }
> > +
> > +       gpiod_set_value_cansleep(ov8856->n_shutdn_gpio, GPIOD_OUT_LOW);
> > +
> > +       ret = regulator_bulk_enable(OV8856_NUM_SUPPLIES, ov8856->supplies);
> > +       if (ret < 0) {
> > +               dev_err(&client->dev, "failed to enable regulators\n");
> > +               goto disable_clk;
> > +       }
> > +
> > +       gpiod_set_value_cansleep(ov8856->n_shutdn_gpio, GPIOD_OUT_HIGH);
>
> To power it up you probably only need:
>
> gpiod_set_value_cansleep(ov8856->n_shutdn_gpio, 0);
>
> And use reset-gpios as active low in your device tree. Assuming the
> reset-gpios is active low like other OmniVision sensors.

Ack.

>
> > +
> > +       usleep_range(1500, 1800);
> > +
> > +       return 0;
> > +
> > +disable_clk:
> > +       clk_disable_unprepare(ov8856->xvclk);
> > +
> > +       return ret;
> > +}
> > +
> > +static void __ov8856_power_off(struct ov8856 *ov8856)
> > +{
> > +       gpiod_set_value_cansleep(ov8856->n_shutdn_gpio, GPIOD_OUT_LOW);
> > +       regulator_bulk_disable(OV8856_NUM_SUPPLIES, ov8856->supplies);
> > +       clk_disable_unprepare(ov8856->xvclk);
> > +}
> > +
> > +
>
> Unneede extra blank line.

Ack.

>
> >         v4l2_i2c_subdev_init(&ov8856->sd, client, &ov8856_subdev_ops);
> > +       ov8856->xvclk = devm_clk_get(&client->dev, "xvclk");
> > +       if (IS_ERR(ov8856->xvclk)) {
> > +               dev_err(&client->dev, "failed to get xvclk\n");
> > +               return -EINVAL;
>
> You should better return the real error insteald
> PTR_ERR(ov8856->xvclk). This way defer probe could work.
>

Ack.

> > +       }
> > +
> > +       ret = clk_set_rate(ov8856->xvclk, OV8856_XVCLK_24);
> > +       if (ret < 0) {
> > +               dev_err(&client->dev, "failed to set xvclk rate (24MHz)\n");
> > +               return ret;
> > +       }
> > +
> > +       ov8856->n_shutdn_gpio = devm_gpiod_get(&client->dev, "reset",
> > +                                              GPIOD_OUT_LOW);
> > +       if (IS_ERR(ov8856->n_shutdn_gpio)) {
> > +               dev_err(&client->dev, "failed to get reset-gpios\n");
> > +               return -EINVAL;
>
> Please return the real error.

Ack.