[PATCH v3 1/2] iio: accel: kionix-kx022a: use scan struct for one-shot and trigger reads

[Gabriel Rondon <grondon@gmail.com>]

The driver kept two separate staging areas that hold the same thing:
buffer[8], a DMA-aligned area used by the one-shot read in
kx022a_get_axis() and by the triggered handler, and the scan struct,
used by the FIFO flush path. Both are three __le16 channels plus room
for the timestamp.

Drop buffer and route the one-shot read and the triggered handler
through scan.channels, so the driver has a single staging area. Move the
IIO_DMA_MINALIGN alignment onto scan, since it now backs the regmap bulk
reads that buffer used to.

No functional change. get_axis() only runs via read_raw() under
iio_device_claim_direct(), so it cannot run while the triggered buffer is
active, and the triggered handler only runs while it is; the two never
touch scan concurrently, exactly as they previously shared buffer.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Gabriel Rondon <grondon@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
 drivers/iio/accel/kionix-kx022a.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/accel/kionix-kx022a.c b/drivers/iio/accel/kionix-kx022a.c
index 02dd1db7a646..93104fdc74b5 100644
--- a/drivers/iio/accel/kionix-kx022a.c
+++ b/drivers/iio/accel/kionix-kx022a.c
@@ -301,11 +301,10 @@ struct kx022a_data {
 	__le16 *fifo_buffer;
 
 	/* 3 x 16bit accel data + timestamp */
-	__le16 buffer[8] __aligned(IIO_DMA_MINALIGN);
 	struct {
 		__le16 channels[3];
 		aligned_s64 ts;
-	} scan;
+	} scan __aligned(IIO_DMA_MINALIGN);
 };
 
 static const struct iio_mount_matrix *
@@ -611,14 +610,14 @@ static int kx022a_get_axis(struct kx022a_data *data,
 			   struct iio_chan_spec const *chan,
 			   int *val)
 {
+	__le16 *buf = &data->scan.channels[0];
 	int ret;
 
-	ret = regmap_bulk_read(data->regmap, chan->address, &data->buffer[0],
-			       sizeof(__le16));
+	ret = regmap_bulk_read(data->regmap, chan->address, buf, sizeof(*buf));
 	if (ret)
 		return ret;
 
-	*val = (s16)le16_to_cpu(data->buffer[0]);
+	*val = (s16)le16_to_cpup(buf);
 
 	return IIO_VAL_INT;
 }
@@ -1029,12 +1028,12 @@ static irqreturn_t kx022a_trigger_handler(int irq, void *p)
 	struct kx022a_data *data = iio_priv(idev);
 	int ret;
 
-	ret = regmap_bulk_read(data->regmap, data->chip_info->xout_l, data->buffer,
-			       KX022A_FIFO_SAMPLES_SIZE_BYTES);
+	ret = regmap_bulk_read(data->regmap, data->chip_info->xout_l,
+			       data->scan.channels, KX022A_FIFO_SAMPLES_SIZE_BYTES);
 	if (ret < 0)
 		goto err_read;
 
-	iio_push_to_buffers_with_timestamp(idev, data->buffer, data->timestamp);
+	iio_push_to_buffers_with_timestamp(idev, &data->scan, data->timestamp);
 err_read:
 	iio_trigger_notify_done(idev->trig);
 
-- 
2.50.1 (Apple Git-155)