Re: [PATCH v2 2/3] iio: chemical: Add support for external Reset and Wakeup in CCS811

[Andy Shevchenko]

On Tue, Apr 14, 2020 at 6:34 PM <mani@xxxxxxxxxx> wrote:
>
> From: Manivannan Sadhasivam <mani@xxxxxxxxxx>
>
> CCS811 VOC sensor exposes nRESET and nWAKE pins which can be connected
> to GPIO pins of the host controller. These pins can be used to externally
> release the device from reset and also to wake it up before any I2C
> transaction. The initial driver support assumed that the nRESET pin is not
> connected and the nWAKE pin is tied to ground.
>
> This commit improves it by adding support for controlling those two pins
> externally using a host controller. For the case of reset, if the hardware
> reset is not available, the mechanism to do software reset is also added.
>
> As a side effect of doing this, the IIO device allocation needs to be
> slightly moved to top of probe to make use of priv data early.

Thank you for an update, my comments below.

...

> +       reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +                                            GPIOD_OUT_LOW);
> +       if (IS_ERR(reset_gpio)) {

> +               dev_err(&client->dev, "Failed to acquire reset gpio\n");

If it's a deferred probe, it would spam the log.

> +               return PTR_ERR(reset_gpio);
> +       }

...

> +               static const u8 reset_seq[] = {
> +                       0xFF, 0x11, 0xE5, 0x72, 0x8A,
> +               };

I would suggest to comment above from where you got this and the
meaning of the numbers.

...

> +       data->wakeup_gpio = devm_gpiod_get_optional(&client->dev, "wakeup",
> +                                                   GPIOD_OUT_HIGH);
> +       if (IS_ERR(data->wakeup_gpio)) {

> +               dev_err(&client->dev, "Failed to acquire wakeup gpio\n");

Ditto.

> +               return PTR_ERR(data->wakeup_gpio);
> +       }

-- 
With Best Regards,
Andy Shevchenko