[PATCH v2 14/16] iio: adc: max1027: Don't just sleep when the EOC interrupt is available

From: Miquel Raynal
Date: Thu Sep 02 2021 - 17:15:22 EST


The interrupt will fire upon end of conversion. This currently can
happen in two situations: either the cnvst trigger was enabled and
toggled, or a single read was requested and the data is ready. The first
situation is already covered while the second is not. Instead, a waiting
delay is applied. Let's handle these interrupts more properly by adding
second path in our EOC helper.

Rename the interrupt handler to a more generic name as it won't only
handle triggered situations.

Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
drivers/iio/adc/max1027.c | 31 ++++++++++++++++++++++++++++---
1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index b85fe0a48ff9..e734d32a5507 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -256,15 +256,27 @@ struct max1027_state {
struct iio_trigger *trig;
__be16 *buffer;
struct mutex lock;
+ struct completion complete;

u8 reg ____cacheline_aligned;
};

static int max1027_wait_eoc(struct iio_dev *indio_dev)
{
+ struct max1027_state *st = iio_priv(indio_dev);
unsigned int conversion_time = MAX1027_CONVERSION_UDELAY;
+ int ret;

- usleep_range(conversion_time, conversion_time * 2);
+ if (st->spi->irq) {
+ ret = wait_for_completion_timeout(&st->complete,
+ msecs_to_jiffies(1000));
+ if (!ret)
+ return ret;
+
+ reinit_completion(&st->complete);
+ } else {
+ usleep_range(conversion_time, conversion_time * 2);
+ }

return 0;
}
@@ -457,12 +469,24 @@ static int max1027_read_scan(struct iio_dev *indio_dev)
return 0;
}

-static irqreturn_t max1027_trigger_handler(int irq, void *private)
+static irqreturn_t max1027_threaded_handler(int irq, void *private)
{
struct iio_poll_func *pf = private;
struct iio_dev *indio_dev = pf->indio_dev;
+ struct max1027_state *st = iio_priv(indio_dev);
int ret;

+ /*
+ * When buffers are disabled, no trigger is in use but if we are here it
+ * means that the device IRQ is enabled:
+ * this is a single read EOC interrupt, we only need to call complete()
+ * and return.
+ */
+ if (!iio_buffer_enabled(indio_dev)) {
+ complete(&st->complete);
+ return IRQ_HANDLED;
+ }
+
ret = max1027_read_scan(indio_dev);
if (ret)
dev_err(&indio_dev->dev,
@@ -501,6 +525,7 @@ static int max1027_probe(struct spi_device *spi)
st->info = &max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];

mutex_init(&st->lock);
+ init_completion(&st->complete);

indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->info = &max1027_info;
@@ -516,7 +541,7 @@ static int max1027_probe(struct spi_device *spi)
if (spi->irq) {
ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
&iio_pollfunc_store_time,
- &max1027_trigger_handler,
+ &max1027_threaded_handler,
NULL);
if (ret < 0) {
dev_err(&indio_dev->dev, "Failed to setup buffer\n");
--
2.27.0