Re: [PATCH 7/8] iio: mma8452: add an attribute to enable the highpass filter

[Martin Fuzzey <mfuzzey@parkeon.com>]

On 23/07/14 20:36, Peter Meerwald wrote:
>> The hardware contains a single configurable highpass filter which
>> is normally used for transient detection (event).
>>
>> However it is also possible to enable this filter for normal channel
>> reading. Add a new attribute in_accel_high_pass_filter_en to do this.
> the patch moves around many lines of code, can likely be made much more
> compact
Well yes it does move some code around but that is because new function 
mma8452_store_hp_cutoff_en(),
introduced as main purpose of this patch, requires access to 
mma8452_change_config(), and indirectly
to mma8452_standby() and mma8452_active()

So this patch moves those three functions earlier in the file.

The only ways I can to see to make it smaller would be:

1) Add a forward declaration for mma8452_change_config()
2) Place mma8452_store_hp_cutoff_en() later in the file.

But for 1) AFAIKT in the kernel forward declarations are avoided when 
possible to avoid introducing double maintenance points.

And for 2) that would break the logical grouping of keeping the 
attribute accessor functions together.

I didn't think the aim was necessarilly to minimize the patch size 
(providing it remains reviewable) but to maximize the quality of the
resulting code once the patch is applied.

So, if no strong objections I'd like to keep this as is.
>   
>> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
>> ---
>>   drivers/iio/accel/mma8452.c |  115 +++++++++++++++++++++++++++++--------------
>>   1 file changed, 78 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
>> index 66933b2..c56d34e 100644
>> --- a/drivers/iio/accel/mma8452.c
>> +++ b/drivers/iio/accel/mma8452.c
>> @@ -62,6 +62,7 @@
>>   #define MMA8452_DATA_CFG_FS_2G 0
>>   #define MMA8452_DATA_CFG_FS_4G 1
>>   #define MMA8452_DATA_CFG_FS_8G 2
>> +#define MMA8452_DATA_CFG_HPF_MASK BIT(4)
>>   
>>   #define MMA8452_INT_DRDY	BIT(0)
>>   #define MMA8452_INT_FF_MT	BIT(2)
>> @@ -106,6 +107,43 @@ static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
>>   		MMA8452_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
>>   }
>>   
>> +static int mma8452_standby(struct mma8452_data *data)
>> +{
>> +	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
>> +		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
>> +}
>> +
>> +static int mma8452_active(struct mma8452_data *data)
>> +{
>> +	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
>> +		data->ctrl_reg1);
>> +}
>> +
>> +static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
>> +{
>> +	int ret;
>> +
>> +	mutex_lock(&data->lock);
>> +
>> +	/* config can only be changed when in standby */
>> +	ret = mma8452_standby(data);
>> +	if (ret < 0)
>> +		goto fail;
>> +
>> +	ret = i2c_smbus_write_byte_data(data->client, reg, val);
>> +	if (ret < 0)
>> +		goto fail;
>> +
>> +	ret = mma8452_active(data);
>> +	if (ret < 0)
>> +		goto fail;
>> +
>> +	ret = 0;
>> +fail:
>> +	mutex_unlock(&data->lock);
>> +	return ret;
>> +}
>> +
>>   static ssize_t mma8452_show_int_plus_micros(char *buf,
>>   	const int (*vals)[2], int n)
>>   {
>> @@ -201,11 +239,50 @@ static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
>>   		ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));
>>   }
>>   
>> +static ssize_t mma8452_show_hp_cutoff_en(struct device *dev,
>> +				struct device_attribute *attr, char *buf)
>> +{
>> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +	struct mma8452_data *data = iio_priv(indio_dev);
>> +
>> +	return sprintf(buf, "%d\n",
>> +		data->data_cfg & MMA8452_DATA_CFG_HPF_MASK ? 1 : 0);
>> +}
>> +
>> +static ssize_t mma8452_store_hp_cutoff_en(struct device *dev,
>> +				struct device_attribute *attr,
>> +				const char *buf, size_t len)
>> +{
>> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +	struct mma8452_data *data = iio_priv(indio_dev);
>> +	bool state;
>> +	int ret;
>> +
>> +	ret = strtobool(buf, &state);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	if (state)
>> +		data->data_cfg |= MMA8452_DATA_CFG_HPF_MASK;
>> +	else
>> +		data->data_cfg &= ~MMA8452_DATA_CFG_HPF_MASK;
>> +
>> +	ret = mma8452_change_config(data, MMA8452_DATA_CFG, data->data_cfg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return len;
>> +}
>> +
>>   static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
>>   static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
>>   	mma8452_show_scale_avail, NULL, 0);
>>   static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,
>>   			S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0);
>> +static IIO_DEVICE_ATTR(in_accel_filter_high_pass_en,
>> +			 S_IRUGO | S_IWUSR,
>> +			 mma8452_show_hp_cutoff_en,
>> +			 mma8452_store_hp_cutoff_en, 0);
>>   
>>   static int mma8452_get_samp_freq_index(struct mma8452_data *data,
>>   	int val, int val2)
>> @@ -282,43 +359,6 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
>>   	return -EINVAL;
>>   }
>>   
>> -static int mma8452_standby(struct mma8452_data *data)
>> -{
>> -	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
>> -		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
>> -}
>> -
>> -static int mma8452_active(struct mma8452_data *data)
>> -{
>> -	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
>> -		data->ctrl_reg1);
>> -}
>> -
>> -static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
>> -{
>> -	int ret;
>> -
>> -	mutex_lock(&data->lock);
>> -
>> -	/* config can only be changed when in standby */
>> -	ret = mma8452_standby(data);
>> -	if (ret < 0)
>> -		goto fail;
>> -
>> -	ret = i2c_smbus_write_byte_data(data->client, reg, val);
>> -	if (ret < 0)
>> -		goto fail;
>> -
>> -	ret = mma8452_active(data);
>> -	if (ret < 0)
>> -		goto fail;
>> -
>> -	ret = 0;
>> -fail:
>> -	mutex_unlock(&data->lock);
>> -	return ret;
>> -}
>> -
>>   static int mma8452_write_raw(struct iio_dev *indio_dev,
>>   			     struct iio_chan_spec const *chan,
>>   			     int val, int val2, long mask)
>> @@ -636,6 +676,7 @@ static struct attribute *mma8452_attributes[] = {
>>   	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
>>   	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
>>   	&iio_dev_attr_in_accel_filter_high_pass_3db_frequency_available.dev_attr.attr,
>> +	&iio_dev_attr_in_accel_filter_high_pass_en.dev_attr.attr,
>>   	NULL
>>   };
>>   
>>
>> --
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