linux-kernel - Re: [PATCH 05/10] iio: accel: BMA220 make use of the watchdog functionality

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Message-ID: <20250907134819.5289f4fa@jic23-huawei>
Date: Sun, 7 Sep 2025 13:48:19 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Petre Rodan <petre.rodan@...dimension.ro>
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, David Lechner
 <dlechner@...libre.com>, Nuno Sá <nuno.sa@...log.com>, Andy
 Shevchenko <andy@...nel.org>
Subject: Re: [PATCH 05/10] iio: accel: BMA220 make use of the watchdog
 functionality

On Mon,  1 Sep 2025 22:47:31 +0300
Petre Rodan <petre.rodan@...dimension.ro> wrote:

> Sometimes the sensor gets stuck and enters a condition in which it pulls
> SDA low, thus making the entire i2c bus unusable.
> The optional bosch,watchdog property mitigates this problem by clearing
> the condition after a period of 1 or 10ms.

As I think was discussed with the binding, I'd turn this on by default
and we can figure out if we want to change that if it causes anyone
problems long run.

> 
> Signed-off-by: Petre Rodan <petre.rodan@...dimension.ro>
> ---
>  drivers/iio/accel/bma220_core.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/iio/accel/bma220_core.c b/drivers/iio/accel/bma220_core.c
> index fae84823d52b..86347cf8ab1e 100644
> --- a/drivers/iio/accel/bma220_core.c
> +++ b/drivers/iio/accel/bma220_core.c
> @@ -158,6 +158,12 @@ enum bma220_axis {
>  	AXIS_Z,
>  };
> 
> +enum bma220_prop_wdt {
> +	BMA220_PROP_WDT_OFF,
> +	BMA220_PROP_WDT_1MS,
> +	BMA220_PROP_WDT_10MS,
> +};
> +
>  static const int bma220_scale_table[][2] = {
>  	{0, 623000}, {1, 248000}, {2, 491000}, {4, 983000},
>  };
> @@ -428,10 +434,17 @@ static int bma220_power(struct bma220_data *data, bool up)
>  	return -EBUSY;
>  }
> 
> +static int bma220_wdt(struct bma220_data *data, const u8 val)
> +{
> +	return regmap_update_bits(data->regmap, BMA220_REG_WDT, BMA220_WDT_MASK,
> +				  FIELD_PREP(BMA220_WDT_MASK, val));
> +}
> +
>  static int bma220_init(struct bma220_data *data)
>  {
>  	int ret;
>  	unsigned int val;
> +	u32 watchdog;
>  	static const char * const regulator_names[] = { "vddd", "vddio", "vdda" };
> 
>  	ret = devm_regulator_bulk_get_enable(data->dev,
> @@ -462,6 +475,25 @@ static int bma220_init(struct bma220_data *data)
>  		return ret;
>  	}
> 
> +	ret = device_property_read_u32(data->dev, "bosch,watchdog", &watchdog);
> +	if (!ret) {
> +		switch (watchdog) {
> +		case BMA220_PROP_WDT_1MS:
> +			ret = bma220_wdt(data, BMA220_WDT_1MS);
> +			break;
> +		case BMA220_PROP_WDT_10MS:
> +			ret = bma220_wdt(data, BMA220_WDT_10MS);
> +			break;
> +		default:
> +			ret = bma220_wdt(data, BMA220_WDT_OFF);
> +			break;
> +		}
> +		if (ret) {
> +			dev_err(data->dev, "Failed to set watchdog\n");

dev_err_probe()

> +			return ret;
> +		}
> +	}
> +
>  	return 0;
>  }
> 
> --
> 2.49.1
> 
>