On 26/04/16 22:36, Srinivas Pandruvada wrote:
> On Tue, 2016-04-26 at 22:15 +0100, Jonathan Cameron wrote:
>>
>> On 26 April 2016 21:25:22 BST, Srinivas Pandruvada <srinivas.pandruva
>> da@xxxxxxxxxxxxxxx> wrote:
>>>
>>> On Mon, 2016-04-25 at 20:31 +0100, Jonathan Cameron wrote:
>>>>
>>>> On 21/04/16 11:49, Steffen Trumtrar wrote:
>>>>>
>>>>>
>>>>> The filter frequency and sample rate have a fixed relationship.
>>>>> Only the filter frequency is unique, however.
>>>>> Currently the driver ignores the filter settings for 32 Hz and
>>>>> 64 Hz.
>>>>>
>>>>> This patch adds the necessary callbacks to be able to configure
>>>>> and read the filter setting from sysfs.
>>>>>
>>>>> Signed-off-by: Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
>>>> cc'd Srinivas as it's his driver... Looks superficially fine to
>>>> me.
>>>>
>>>> Jonathan
>>>>>
>>>>>
>>>>> ---
>>>>>
>>>>> Changing the sample rate will result in using the first match
>>>>> and therefore selecting the filter accordingly. Is this a
>>>>> misuse
>>>>> of the ABI and should be handled differently or is this okay?
>>>>>
>>> This is the reason they were omitted. Now you can't uniquely set
>>> 100Hz
>>> sampling frequency. Depending on filter it will have different
>>> results.
>>>
>>> I think this needs some ABI level changes, where you display
>>> available
>>> and allow to specify both ODR and Filter to uniquely select.
>> Unfortunately the moment the ABI allows for combined elements it
>> becomes a
>> nightmare for complexity. In some devices a single parameter change
>> can
>> change everything else. There are no simple rules unfortunately.
>>
>> The way we avoid this being a problem is that we very deliberately
>> allow any ABI element
>> to be able to result in a change in any other. This includes
>> changing the
>> available values list as here. It might be slightly nicer to jump to
>> the nearest
>> available option though.
>>
>> An alternative would be to have an interface to fake such changes
>> then
>> apply them atomically if possible.
>> That level of complexity just does seem warranted here and would
>> still need userspace to check valid ranges as it
>> pretends to change the state. Hence no real gain....
>>
> I think we should add some documentation for this driver about this.
> They should rather change filer rather than sampling freq to have
> unique setting.
whilst that would get around the problem, people are going to be expecting
to have explicit control of sampling frequency if they see it is variable for
the part...
Tricky unfortunately.
Jonathan
>
> Thanks,
> Srinivas
>
>> Jonathan
>>>
>>>
>>> Thanks,
>>> Srinivas
>>>
>>>
>>>>
>>>>>
>>>>> drivers/iio/gyro/bmg160_core.c | 105
>>>>> ++++++++++++++++++++++++++++++++++++-----
>>>>> 1 file changed, 93 insertions(+), 12 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iio/gyro/bmg160_core.c
>>>>> b/drivers/iio/gyro/bmg160_core.c
>>>>> index bbce3b09ac45..ea0243eb393a 100644
>>>>> --- a/drivers/iio/gyro/bmg160_core.c
>>>>> +++ b/drivers/iio/gyro/bmg160_core.c
>>>>> @@ -52,6 +52,7 @@
>>>>> #define BMG160_REG_PMU_BW 0x10
>>>>> #define BMG160_NO_FILTER 0
>>>>> #define BMG160_DEF_BW 100
>>>>> +#define BMG160_REG_PMU_BW_RES BIT(7)
>>>>>
>>>>> #define BMG160_REG_INT_MAP_0 0x17
>>>>> #define BMG160_INT_MAP_0_BIT_ANY BIT(1)
>>>>> @@ -103,7 +104,6 @@ struct bmg160_data {
>>>>> struct iio_trigger *motion_trig;
>>>>> struct mutex mutex;
>>>>> s16 buffer[8];
>>>>> - u8 bw_bits;
>>>>> u32 dps_range;
>>>>> int ev_enable_state;
>>>>> int slope_thres;
>>>>> @@ -119,13 +119,16 @@ enum bmg160_axis {
>>>>> };
>>>>>
>>>>> static const struct {
>>>>> - int val;
>>>>> + int odr;
>>>>> + int filter;
>>>>> int bw_bits;
>>>>> -} bmg160_samp_freq_table[] = { {100, 0x07},
>>>>> - {200, 0x06},
>>>>> - {400, 0x03},
>>>>> - {1000, 0x02},
>>>>> - {2000, 0x01} };
>>>>> +} bmg160_samp_freq_table[] = { {100, 32, 0x07},
>>>>> + {200, 64, 0x06},
>>>>> + {100, 12, 0x05},
>>>>> + {200, 23, 0x04},
>>>>> + {400, 47, 0x03},
>>>>> + {1000, 116, 0x02},
>>>>> + {2000, 230, 0x01} };
>>>>>
>>>>> static const struct {
>>>>> int scale;
>>>>> @@ -154,7 +157,7 @@ static int bmg160_convert_freq_to_bit(int
>>>>> val)
>>>>> int i;
>>>>>
>>>>> for (i = 0; i < ARRAY_SIZE(bmg160_samp_freq_table);
>>>>> ++i) {
>>>>> - if (bmg160_samp_freq_table[i].val == val)
>>>>> + if (bmg160_samp_freq_table[i].odr == val)
>>>>> return
>>>>> bmg160_samp_freq_table[i].bw_bits;
>>>>> }
>>>>>
>>>>> @@ -176,7 +179,51 @@ static int bmg160_set_bw(struct
>>>>> bmg160_data
>>>>> *data, int val)
>>>>> return ret;
>>>>> }
>>>>>
>>>>> - data->bw_bits = bw_bits;
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int bmg160_get_filter(struct bmg160_data *data, int
>>>>> *val)
>>>>> +{
>>>>> + int ret;
>>>>> + int i;
>>>>> + unsigned int bw_bits;
>>>>> +
>>>>> + ret = regmap_read(data->regmap, BMG160_REG_PMU_BW,
>>>>> &bw_bits);
>>>>> + if (ret < 0) {
>>>>> + dev_err(data->dev, "Error reading
>>>>> reg_pmu_bw\n");
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + /* Ignore the readonly reserved bit. */
>>>>> + bw_bits &= ~BMG160_REG_PMU_BW_RES;
>>>>> +
>>>>> + for (i = 0; i < ARRAY_SIZE(bmg160_samp_freq_table);
>>>>> ++i) {
>>>>> + if (bmg160_samp_freq_table[i].bw_bits ==
>>>>> bw_bits)
>>>>> + break;
>>>>> + }
>>>>> +
>>>>> + *val = bmg160_samp_freq_table[i].filter;
>>>>> +
>>>>> + return ret ? ret : IIO_VAL_INT;
>>>>> +}
>>>>> +
>>>>> +
>>>>> +static int bmg160_set_filter(struct bmg160_data *data, int
>>>>> val)
>>>>> +{
>>>>> + int ret;
>>>>> + int i;
>>>>> +
>>>>> + for (i = 0; i < ARRAY_SIZE(bmg160_samp_freq_table);
>>>>> ++i) {
>>>>> + if (bmg160_samp_freq_table[i].filter == val)
>>>>> + break;
>>>>> + }
>>>>> +
>>>>> + ret = regmap_write(data->regmap, BMG160_REG_PMU_BW,
>>>>> + bmg160_samp_freq_table[i].bw_bits);
>>>>> + if (ret < 0) {
>>>>> + dev_err(data->dev, "Error writing
>>>>> reg_pmu_bw\n");
>>>>> + return ret;
>>>>> + }
>>>>>
>>>>> return 0;
>>>>> }
>>>>> @@ -388,10 +435,21 @@ static int
>>>>> bmg160_setup_new_data_interrupt(struct bmg160_data *data,
>>>>> static int bmg160_get_bw(struct bmg160_data *data, int *val)
>>>>> {
>>>>> int i;
>>>>> + unsigned int bw_bits;
>>>>> + int ret;
>>>>> +
>>>>> + ret = regmap_read(data->regmap, BMG160_REG_PMU_BW,
>>>>> &bw_bits);
>>>>> + if (ret < 0) {
>>>>> + dev_err(data->dev, "Error reading
>>>>> reg_pmu_bw\n");
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + /* Ignore the readonly reserved bit. */
>>>>> + bw_bits &= ~BMG160_REG_PMU_BW_RES;
>>>>>
>>>>> for (i = 0; i < ARRAY_SIZE(bmg160_samp_freq_table);
>>>>> ++i) {
>>>>> - if (bmg160_samp_freq_table[i].bw_bits == data-
>>>>>>
>>>>>> bw_bits) {
>>>>> - *val = bmg160_samp_freq_table[i].val;
>>>>> + if (bmg160_samp_freq_table[i].bw_bits ==
>>>>> bw_bits)
>>>>> {
>>>>> + *val = bmg160_samp_freq_table[i].odr;
>>>>> return IIO_VAL_INT;
>>>>> }
>>>>> }
>>>>> @@ -506,6 +564,8 @@ static int bmg160_read_raw(struct iio_dev
>>>>> *indio_dev,
>>>>> return IIO_VAL_INT;
>>>>> } else
>>>>> return -EINVAL;
>>>>> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>>>>> + return bmg160_get_filter(data, val);
>>>>> case IIO_CHAN_INFO_SCALE:
>>>>> *val = 0;
>>>>> switch (chan->type) {
>>>>> @@ -570,6 +630,26 @@ static int bmg160_write_raw(struct iio_dev
>>>>> *indio_dev,
>>>>> ret = bmg160_set_power_state(data, false);
>>>>> mutex_unlock(&data->mutex);
>>>>> return ret;
>>>>> + case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>>>>> + if (val2)
>>>>> + return -EINVAL;
>>>>> +
>>>>> + mutex_lock(&data->mutex);
>>>>> + ret = bmg160_set_power_state(data, true);
>>>>> + if (ret < 0) {
>>>>> + bmg160_set_power_state(data, false);
>>>>> + mutex_unlock(&data->mutex);
>>>>> + return ret;
>>>>> + }
>>>>> + ret = bmg160_set_filter(data, val);
>>>>> + if (ret < 0) {
>>>>> + bmg160_set_power_state(data, false);
>>>>> + mutex_unlock(&data->mutex);
>>>>> + return ret;
>>>>> + }
>>>>> + ret = bmg160_set_power_state(data, false);
>>>>> + mutex_unlock(&data->mutex);
>>>>> + return ret;
>>>>> case IIO_CHAN_INFO_SCALE:
>>>>> if (val)
>>>>> return -EINVAL;
>>>>> @@ -727,7 +807,8 @@ static const struct iio_event_spec
>>>>> bmg160_event
>>>>> = {
>>>>> .channel2 = IIO_MOD_##_axis,
>>>>> \
>>>>> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>>>>> \
>>>>> .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
>>>>>
>>>>> \
>>>>> - BIT(IIO_CHAN_INFO_SAMP_FRE
>>>>> Q),
>>>>> \
>>>>> + BIT(IIO_CHAN_INFO_SAMP_FREQ) |
>>>>> \
>>>>> + BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENC
>>>>> Y),
>>>>> \
>>>>> .scan_index = AXIS_##_axis,
>>>>> \
>>>>> .scan_type = {
>>>>> \
>>>>> .sign = 's',
>>>>> \
>>>>>
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