[PATCH v3 5/6] iio: accel: sca3300: use IIO_DECLARE_BUFFER_WITH_TS

David Lechner
2025-04-25T21:23:53Z

Use IIO_DECLARE_BUFFER_WITH_TS() to declare the buffer that gets used
with iio_push_to_buffers_with_ts(). This makes the code a bit easier to
read and understand.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
This is an alternative to [1]. Also, this serves as a test to see if we
can get a rule of thumb to decide how much is too much to put on the
stack vs. needing to put the buffer in a static struct. SCA3300_SCAN_MAX
is 7, so this add a bit over 64 bytes to the stack, make the stack now
roughly double what it was before.

[1]: https://lore.kernel.org/linux-iio/20250418-iio-prefer-aligned_s64-timestamp-v1-1-4c6080710516@baylibre.com/
---
drivers/iio/accel/sca3300.c | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
index 1132bbaba75bcca525fac2f3e19f63546380fd4f..67416a406e2f43e4e417210410904d44c93111d2 100644
--- a/drivers/iio/accel/sca3300.c
+++ b/drivers/iio/accel/sca3300.c
@@ -58,15 +58,6 @@ enum sca3300_scan_indexes {
SCA3300_SCAN_MAX
};

-/*
- * Buffer size max case:
- * Three accel channels, two bytes per channel.
- * Temperature channel, two bytes.
- * Three incli channels, two bytes per channel.
- * Timestamp channel, eight bytes.
- */
-#define SCA3300_MAX_BUFFER_SIZE (ALIGN(sizeof(s16) * SCA3300_SCAN_MAX, sizeof(s64)) + sizeof(s64))
-
#define SCA3300_ACCEL_CHANNEL(index, reg, axis) { \
.type = IIO_ACCEL, \
.address = reg, \
@@ -193,9 +184,6 @@ struct sca3300_chip_info {
* @spi: SPI device structure
* @lock: Data buffer lock
* @chip: Sensor chip specific information
- * @buffer: Triggered buffer:
- * -SCA3300: 4 channel 16-bit data + 64-bit timestamp
- * -SCL3300: 7 channel 16-bit data + 64-bit timestamp
* @txbuf: Transmit buffer
* @rxbuf: Receive buffer
*/
@@ -203,7 +191,6 @@ struct sca3300_data {
struct spi_device *spi;
struct mutex lock;
const struct sca3300_chip_info *chip;
- u8 buffer[SCA3300_MAX_BUFFER_SIZE] __aligned(sizeof(s64));
u8 txbuf[4] __aligned(IIO_DMA_MINALIGN);
u8 rxbuf[4];
};
@@ -492,7 +479,7 @@ static irqreturn_t sca3300_trigger_handler(int irq, void *p)
struct iio_dev *indio_dev = pf->indio_dev;
struct sca3300_data *data = iio_priv(indio_dev);
int bit, ret, val, i = 0;
- s16 *channels = (s16 *)data->buffer;
+ IIO_DECLARE_BUFFER_WITH_TS(s16, channels, SCA3300_SCAN_MAX);

iio_for_each_active_channel(indio_dev, bit) {
ret = sca3300_read_reg(data, indio_dev->channels[bit].address, &val);
@@ -505,8 +492,7 @@ static irqreturn_t sca3300_trigger_handler(int irq, void *p)
channels[i++] = val;
}

- iio_push_to_buffers_with_ts(indio_dev, data->buffer,
- sizeof(data->buffer),
+ iio_push_to_buffers_with_ts(indio_dev, channels, sizeof(channels),
iio_get_time_ns(indio_dev));
out:
iio_trigger_notify_done(indio_dev->trig);

--
2.43.0