[PATCH v3] iio: accell: mma8452: Reduce sleep time when data not ready

From: Richard Tresidder <rtresidd@electromag.com.au>
To: Martin Kepplinger <martink@posteo.de>, linux-iio@vger.kernel.org
Cc: Jonathan Cameron <jic23@kernel.org>,
	knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net,
	harinath922@gmail.com
Subject: [PATCH v3] iio: accell: mma8452: Reduce sleep time when data not ready
Date: Tue, 8 May 2018 16:19:02 +0800	[thread overview]
Message-ID: <cd307679-19c5-1132-79dc-b28c96cc537e@electromag.com.au> (raw)
In-Reply-To: <939563a6-19ff-b51a-3a26-e90f10c7bae1@posteo.de>

Modified the sleep method when data is not ready to allow for sampling > 50sps to work.

Signed-off-by: Richard Tresidder <rtresidd@electromag.com.au>
---
v3: Changes from v2
  * Removed fallthrough fix (will submit separately)
  * Fixed some blank lines, trailing white spaces.

v2: Changes from v1
  * Remove whitespace changes
  * Added fallthrough fix (subsequently removed)

drivers/iio/accel/mma8452.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 7a2da7f..5650b59 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -106,6 +106,7 @@ struct mma8452_data {
 	u8 ctrl_reg1;
 	u8 data_cfg;
 	const struct mma_chip_info *chip_info;
+	int sleep_val;
 };
 
  /**
@@ -193,7 +194,10 @@ static int mma8452_drdy(struct mma8452_data *data)
 		if ((ret & MMA8452_STATUS_DRDY) == MMA8452_STATUS_DRDY)
 			return 0;
 
-		msleep(20);
+		if (data->sleep_val <= 20)
+			usleep_range(data->sleep_val * 250, data->sleep_val * 500);
+		else
+			msleep(20);
 	}
 
 	dev_err(&data->client->dev, "data not ready\n");
@@ -544,6 +548,18 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
+static int mma8452_calculate_sleep(struct mma8452_data *data)
+{
+	int ret, i = mma8452_get_odr_index(data);
+
+	if (mma8452_samp_freq[i][0] > 0)
+		ret = 1000 / mma8452_samp_freq[i][0];
+	else
+		ret = 1000;
+
+	return ret == 0 ? 1 : ret;
+}
+
 static int mma8452_standby(struct mma8452_data *data)
 {
 	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
@@ -700,6 +716,8 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
 		data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
 		data->ctrl_reg1 |= i << MMA8452_CTRL_DR_SHIFT;
 
+		data->sleep_val = mma8452_calculate_sleep(data);
+
 		ret = mma8452_change_config(data, MMA8452_CTRL_REG1,
 					    data->ctrl_reg1);
 		break;
@@ -1593,6 +1611,9 @@ static int mma8452_probe(struct i2c_client *client,
 
 	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
 			  (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
+
+	data->sleep_val = mma8452_calculate_sleep(data);
+
 	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
 					data->ctrl_reg1);
 	if (ret < 0)
