Hello,
sorry first for the desastrous text formatting.
The main idea behind is to be backward compatible with existing setup. Otherwise using i2c-mux to do nothing is not very useful. But this way we ensure backward compatibility and gain the advantage of not having to do i2c transaction with the mpu chip before every transaction with the auxiliary chip.
JB
From: Jonathan Cameron <jic23@xxxxxxxxxx>
Sent: Saturday, February 15, 2020 18:30
To: Jean-Baptiste Maneyrol <JManeyrol@xxxxxxxxxxxxxx>
Cc: linux-iio@xxxxxxxxxxxxxxx <linux-iio@xxxxxxxxxxxxxxx>; Peter Rosin <peda@xxxxxxxxxx>
Subject: Re: [PATCH 01/13] iio: imu: inv_mpu6050: enable i2c aux mux bypass only once
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On Wed, 12 Feb 2020 18:40:36 +0100
Jean-Baptiste Maneyrol <jmaneyrol@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
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);
