linux-kernel - Re: [PATCH v3 2/3] media: ov8856: Add devicetree support

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Date:   Tue, 31 Mar 2020 17:01:00 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Robert Foss <robert.foss@...aro.org>
Cc:     Dongchun Zhu <dongchun.zhu@...iatek.com>,
        Fabio Estevam <festevam@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Tomasz Figa <tfiga@...omium.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 2/3] media: ov8856: Add devicetree support

On Tue, Mar 31, 2020 at 4:36 PM Robert Foss <robert.foss@...aro.org> wrote:
>
> Add devicetree match table, and enable ov8856_probe()
> to initialize power, clocks and reset pins.

...

> +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;
> +       }
> +

> +       if (is_acpi_node(ov8856->dev->fwnode))

Use dev_fwnode().

> +               return 0;
> +
> +       if (ov8856->reset_gpio) {

> +               gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_HIGH);

This is wrong. You have to fix it to use either 0 or 1.

> +               usleep_range(1000, 2000);
> +       }
> +
> +       ret = regulator_bulk_enable(ARRAY_SIZE(ov8856_supply_names),
> +                                   ov8856->supplies);

> +       if (ret < 0) {

Do you need all ' < 0' parts all over the series?

> +               dev_err(&client->dev, "failed to enable regulators\n");
> +               goto disable_clk;
> +       }

...

> +       gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_LOW);

Ditto.

...

> +       gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_HIGH);

Ditto.

...

> +       gpiod_set_value_cansleep(ov8856->reset_gpio, GPIOD_OUT_HIGH);

Ditto.

...

> -       ret = fwnode_property_read_u32(fwnode, "clock-frequency", &mclk);
> -       if (ret)
> -               return ret;

Where is it gone? Why?

> +       ov8856->xvclk = devm_clk_get_optional(dev, "xvclk");
> +       if (IS_ERR(ov8856->xvclk)) {

> +               dev_err(dev, "could not get xvclk clock (%ld)\n",
> +                       PTR_ERR(ov8856->xvclk));

Also you may use %pe here and in similar cases.

> +               return PTR_ERR(ov8856->xvclk);
> +       }

> +       ov8856->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> +               GPIOD_OUT_HIGH);

Here parameter is correct. The question is, what the value should be
HIGH or LOW?
Basically HIGH means to assert the signal.

> +       if (IS_ERR(ov8856->reset_gpio)) {

> +               dev_dbg(dev, "failed to get reset-gpio\n");

Noise.
Enable GPIO debug to see this kind of messages.

> +               return PTR_ERR(ov8856->reset_gpio);
> +       }

...

> +       ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ov8856_supply_names),
> +                                     ov8856->supplies);
> +       if (ret) {

> +               dev_warn(dev, "failed to get regulators\n");

If it's a warning, why we return from here?
Same question to all other places with same issue.

> +               return ret;
>         }

-- 
With Best Regards,
Andy Shevchenko