Re: [PATCH 01/13] iio: imu: inv_mpu6050: enable i2c aux mux bypass only once

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 12 Feb 2020 18:40:36 +0100
Jean-Baptiste Maneyrol <jmaneyrol@invensense.com> wrote:

> i2c auxiliary mux is done by analog switches. You do not need to
> set them for every i2c transfer.
> Just set i2c bypass bit at init and do noting in i2c de/select.
> 
> Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Fair enough.  Given we are making the decision based on DT and that
can't change on reprobing etc so this change makes sense to me I think.

It does leave us making rather odd use of the mux code, so I'd
just like Peter to take a quick look at this before I apply it.

Jonathan

> ---
>  drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c | 71 +++++++++--------------
>  1 file changed, 28 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c
> index 1363d3776523..24df880248f2 100644
> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c
> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c
> @@ -20,38 +20,6 @@ static const struct regmap_config inv_mpu_regmap_config = {
>  
>  static int inv_mpu6050_select_bypass(struct i2c_mux_core *muxc, u32 chan_id)
>  {
> -	struct iio_dev *indio_dev = i2c_mux_priv(muxc);
> -	struct inv_mpu6050_state *st = iio_priv(indio_dev);
> -	int ret;
> -
> -	mutex_lock(&st->lock);
> -
> -	ret = inv_mpu6050_set_power_itg(st, true);
> -	if (ret)
> -		goto error_unlock;
> -
> -	ret = regmap_write(st->map, st->reg->int_pin_cfg,
> -			   st->irq_mask | INV_MPU6050_BIT_BYPASS_EN);
> -
> -error_unlock:
> -	mutex_unlock(&st->lock);
> -
> -	return ret;
> -}
> -
> -static int inv_mpu6050_deselect_bypass(struct i2c_mux_core *muxc, u32 chan_id)
> -{
> -	struct iio_dev *indio_dev = i2c_mux_priv(muxc);
> -	struct inv_mpu6050_state *st = iio_priv(indio_dev);
> -
> -	mutex_lock(&st->lock);
> -
> -	/* It doesn't really matter if any of the calls fail */
> -	regmap_write(st->map, st->reg->int_pin_cfg, st->irq_mask);
> -	inv_mpu6050_set_power_itg(st, false);
> -
> -	mutex_unlock(&st->lock);
> -
>  	return 0;
>  }
>  
> @@ -79,19 +47,20 @@ static bool inv_mpu_i2c_aux_bus(struct device *dev)
>  	}
>  }
>  
> -/*
> - * MPU9xxx magnetometer support requires to disable i2c auxiliary bus support.
> - * To ensure backward compatibility with existing setups, do not disable
> - * i2c auxiliary bus if it used.
> - * Check for i2c-gate node in devicetree and set magnetometer disabled.
> - * Only MPU6500 is supported by ACPI, no need to check.
> - */
> -static int inv_mpu_magn_disable(struct iio_dev *indio_dev)
> +static int inv_mpu_i2c_aux_setup(struct iio_dev *indio_dev)
>  {
>  	struct inv_mpu6050_state *st = iio_priv(indio_dev);
>  	struct device *dev = indio_dev->dev.parent;
>  	struct device_node *mux_node;
> +	int ret;
>  
> +	/*
> +	 * MPU9xxx magnetometer support requires to disable i2c auxiliary bus.
> +	 * To ensure backward compatibility with existing setups, do not disable
> +	 * i2c auxiliary bus if it used.
> +	 * Check for i2c-gate node in devicetree and set magnetometer disabled.
> +	 * Only MPU6500 is supported by ACPI, no need to check.
> +	 */
>  	switch (st->chip_type) {
>  	case INV_MPU9150:
>  	case INV_MPU9250:
> @@ -107,7 +76,24 @@ static int inv_mpu_magn_disable(struct iio_dev *indio_dev)
>  		break;
>  	}
>  
> +	/* enable i2c bypass when using i2c auxiliary bus */
> +	if (inv_mpu_i2c_aux_bus(dev)) {
> +		ret = inv_mpu6050_set_power_itg(st, true);
> +		if (ret)
> +			return ret;
> +		ret = regmap_write(st->map, st->reg->int_pin_cfg,
> +				   st->irq_mask | INV_MPU6050_BIT_BYPASS_EN);
> +		if (ret)
> +			goto error;
> +		ret = inv_mpu6050_set_power_itg(st, false);
> +		if (ret)
> +			goto error;
> +	}
> +
>  	return 0;
> +error:
> +	inv_mpu6050_set_power_itg(st, false);
> +	return ret;
>  }
>  
>  /**
> @@ -151,7 +137,7 @@ static int inv_mpu_probe(struct i2c_client *client,
>  	}
>  
>  	result = inv_mpu_core_probe(regmap, client->irq, name,
> -				    inv_mpu_magn_disable, chip_type);
> +				    inv_mpu_i2c_aux_setup, chip_type);
>  	if (result < 0)
>  		return result;
>  
> @@ -160,8 +146,7 @@ static int inv_mpu_probe(struct i2c_client *client,
>  		/* declare i2c auxiliary bus */
>  		st->muxc = i2c_mux_alloc(client->adapter, &client->dev,
>  					 1, 0, I2C_MUX_LOCKED | I2C_MUX_GATE,
> -					 inv_mpu6050_select_bypass,
> -					 inv_mpu6050_deselect_bypass);
> +					 inv_mpu6050_select_bypass, NULL);
>  		if (!st->muxc)
>  			return -ENOMEM;
>  		st->muxc->priv = dev_get_drvdata(&client->dev);