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input: mpu3050: adjust LPF bandwidth according to sampling frequency.

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Low pass filter bandwidth is configured to be equal to or greater than
half of the sampling freqency.

Signed-off-by: Wentao Xu <wentaox@codeaurora.org>
(cherry picked from commit 04f4cc9ff3707a39af39c23cc9f3aeb5c344c60c)

Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
(cherry picked from commit a7d8fe1d40061ec56c938308d8f7265f29b146c1)

Change-Id: I796d30d474aa64c1679781b38ca5f151b37c92fd
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
This commit is contained in:
Wentao Xu 2012-08-15 19:41:43 -04:00 committed by Stephen Boyd
parent 1402ceabfa
commit 589acb3c40
1 changed files with 59 additions and 7 deletions
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66
drivers/input/misc/mpu3050.c
View file

@ -123,6 +123,7 @@ struct mpu3050_sensor {
struct delayed_work input_work;
u32 use_poll;
u32 poll_interval;
u32 dlpf_index;
};
struct sensor_regulator {
@ -137,6 +138,39 @@ struct sensor_regulator mpu_vreg[] = {
{NULL, "vlogic", 1800000, 1800000},
};
struct dlpf_cfg_tb {
u8 cfg; /* cfg index */
u32 lpf_bw; /* low pass filter bandwidth in Hz */
u32 sample_rate; /* analog sample rate in Khz, 1 or 8 */
};
static struct dlpf_cfg_tb dlpf_table[] = {
{6, 5, 1},
{5, 10, 1},
{4, 20, 1},
{3, 42, 1},
{2, 98, 1},
{1, 188, 1},
{0, 256, 8},
};
static u8 interval_to_dlpf_cfg(u32 interval)
{
u32 sample_rate = 1000 / interval;
u32 i;
/* the filter bandwidth needs to be greater or
* equal to half of the sample rate
*/
for (i = 0; i < sizeof(dlpf_table)/sizeof(dlpf_table[0]); i++) {
if (dlpf_table[i].lpf_bw * 2 >= sample_rate)
return i;
}
/* return the maximum possible */
return --i;
}
static int mpu3050_config_regulator(struct i2c_client *client, bool on)
{
int rc = 0, i;
@ -217,6 +251,9 @@ static ssize_t mpu3050_attr_set_polling_rate(struct device *dev,
{
struct mpu3050_sensor *sensor = dev_get_drvdata(dev);
unsigned long interval_ms;
unsigned int dlpf_index;
u8 divider, reg;
int ret;
if (kstrtoul(buf, 10, &interval_ms))
return -EINVAL;
@ -224,12 +261,27 @@ static ssize_t mpu3050_attr_set_polling_rate(struct device *dev,
(interval_ms > MPU3050_MAX_POLL_INTERVAL))
return -EINVAL;
if (sensor)
sensor->poll_interval = interval_ms;
dlpf_index = interval_to_dlpf_cfg(interval_ms);
divider = interval_ms * dlpf_table[dlpf_index].sample_rate - 1;
/* Output frequency divider. The poll interval */
i2c_smbus_write_byte_data(sensor->client, MPU3050_SMPLRT_DIV,
interval_ms - 1);
if (sensor->dlpf_index != dlpf_index) {
/* Set low pass filter and full scale */
reg = dlpf_table[dlpf_index].cfg;
reg |= MPU3050_DEFAULT_FS_RANGE << 3;
reg |= MPU3050_EXT_SYNC_NONE << 5;
ret = i2c_smbus_write_byte_data(sensor->client,
MPU3050_DLPF_FS_SYNC, reg);
if (ret == 0)
sensor->dlpf_index = dlpf_index;
}
if (sensor->poll_interval != interval_ms) {
/* Output frequency divider. The poll interval */
ret = i2c_smbus_write_byte_data(sensor->client,
MPU3050_SMPLRT_DIV, divider);
if (ret == 0)
sensor->poll_interval = interval_ms;
}
return size;
}
@ -482,8 +534,8 @@ static int __devinit mpu3050_hw_init(struct mpu3050_sensor *sensor)
return ret;
/* Set low pass filter and full scale */
reg = MPU3050_DEFAULT_FS_RANGE;
reg |= MPU3050_DLPF_CFG_42HZ << 3;
reg = MPU3050_DLPF_CFG_42HZ;
reg |= MPU3050_DEFAULT_FS_RANGE << 3;
reg |= MPU3050_EXT_SYNC_NONE << 5;
ret = i2c_smbus_write_byte_data(client, MPU3050_DLPF_FS_SYNC, reg);
if (ret < 0)