[PATCH v4 06/17] iio: magnetometer: ak8975: modernize polling loops with iopoll() macros

Joshua Crofts via B4 Relay
2026-05-04T09:48:35Z

From: Joshua Crofts <joshua.crofts1@gmail.com>

The driver currently uses while loops and msleep() for polling during
conversion waits.

Replace the custom polling loops with readx_poll_timeout() and
read_poll_timeout() macros from <linux/iopoll.h>. This reduces
boilerplate, standardizes timeout handling and improves overall code
readability, keeping the original timing and error behaviour. Add
<linux/time.h> for USEC_PER_MSEC macro instead of using magic numbers.

Assisted-by: Gemini:3.1-Pro
Co-developed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
---
drivers/iio/magnetometer/ak8975.c | 45 +++++++++++++++++----------------------
1 file changed, 19 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 57f50c09cca539c3733f516a1617375e9134c349..2e750c151435da57926969a63ba9fe996d774e7a 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -23,6 +23,7 @@
#include <linux/pm_runtime.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
+#include <linux/time.h>
#include <linux/types.h>
#include <linux/wait.h>

@@ -652,18 +653,15 @@ static int ak8975_setup(struct i2c_client *client)
static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
struct i2c_client *client = data->client;
- u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
int ret;
+ int val;

/* Wait for the conversion to complete. */
- while (timeout_ms) {
- msleep(AK8975_CONVERSION_DONE_POLL_TIME);
- if (gpiod_get_value(data->eoc_gpiod))
- break;
- timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
- }
- if (!timeout_ms)
- return -ETIMEDOUT;
+ ret = readx_poll_timeout(gpiod_get_value, data->eoc_gpiod, val, val != 0,
+ AK8975_CONVERSION_DONE_POLL_TIME * USEC_PER_MSEC,
+ AK8975_MAX_CONVERSION_TIMEOUT * USEC_PER_MSEC);
+ if (ret)
+ return ret;

ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
if (ret < 0)
@@ -675,28 +673,23 @@ static int wait_conversion_complete_gpio(struct ak8975_data *data)
static int wait_conversion_complete_polled(struct ak8975_data *data)
{
struct i2c_client *client = data->client;
- u8 read_status;
- u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
int ret;
+ int val;

/* Wait for the conversion to complete. */
- while (timeout_ms) {
- msleep(AK8975_CONVERSION_DONE_POLL_TIME);
- ret = i2c_smbus_read_byte_data(client,
- data->def->ctrl_regs[ST1]);
- if (ret < 0) {
- dev_err(&client->dev, "Error in reading ST1\n");
- return ret;
- }
- read_status = ret;
- if (read_status)
- break;
- timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
+ ret = read_poll_timeout(i2c_smbus_read_byte_data, val, val != 0,
+ AK8975_CONVERSION_DONE_POLL_TIME * USEC_PER_MSEC,
+ AK8975_MAX_CONVERSION_TIMEOUT * USEC_PER_MSEC,
+ true,
+ client, data->def->ctrl_regs[ST1]);
+ if (ret)
+ return ret;
+ if (val < 0) {
+ dev_err(&client->dev, "Error in reading ST1\n");
+ return val;
}
- if (!timeout_ms)
- return -ETIMEDOUT;

- return read_status;
+ return val;
}

/* Returns 0 if the end of conversion interrupt occurred or -ETIMEDOUT otherwise */

--
2.47.3