Messages in this thread |  | | Date | Mon, 4 May 2026 16:06:06 +0100 | | From | Jonathan Cameron <> | | Subject | Re: [PATCH v4 06/17] iio: magnetometer: ak8975: modernize polling loops with iopoll() macros |
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On Mon, 04 May 2026 11:48:18 +0200 Joshua Crofts via B4 Relay <devnull+joshua.crofts1.gmail.com@kernel.org> wrote:
> 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>
One question inline on whether it is a good idea to be paranoid about gpiod_get_value() potentially returning < 0 to indicate an error. Right now that is treated as success.
> --- > 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;
Should we check val as well? It might be negative if gpiod_get_value() returned an error.. Obviously the original code didn't so this would be an improvement rather than maintaining what that was doing.
> > 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 */ >
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