[PATCH v3 2/6] iio: adc: ad4695: use u16 for buffer elements

David Lechner
2025-04-25T21:18:11Z

Change the type of the buffer elements to u16 since we currently only
support 16-bit word size. The code was originally written to also allow
for 32-bit word size when oversampling is enabled, but so far,
oversampling is only implemented when using SPI offload and therefore
doesn't use this buffer.

AD4695_MAX_CHANNEL_SIZE macro is dropped since it no longer adds any
value.

AD4695_MAX_CHANNELS + 2 is changed to AD4695_MAX_CHANNELS + 1 because
previously we were overallocating. AD4695_MAX_CHANNELS is the number of
of voltage channels and + 1 is for the temperature channel.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
drivers/iio/adc/ad4695.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c
index 68c6625db0d75f4cade7cb029e94191118dbcaa0..0c633d43e480d5404074e9fa35f1d330b448f0a2 100644
--- a/drivers/iio/adc/ad4695.c
+++ b/drivers/iio/adc/ad4695.c
@@ -106,8 +106,6 @@

/* Max number of voltage input channels. */
#define AD4695_MAX_CHANNELS 16
-/* Max size of 1 raw sample in bytes. */
-#define AD4695_MAX_CHANNEL_SIZE 2

enum ad4695_in_pair {
AD4695_IN_PAIR_REFGND,
@@ -162,8 +160,8 @@ struct ad4695_state {
struct spi_transfer buf_read_xfer[AD4695_MAX_CHANNELS * 2 + 3];
struct spi_message buf_read_msg;
/* Raw conversion data received. */
- u8 buf[ALIGN((AD4695_MAX_CHANNELS + 2) * AD4695_MAX_CHANNEL_SIZE,
- sizeof(s64)) + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
+ u16 buf[ALIGN((AD4695_MAX_CHANNELS + 1) * sizeof(u16),
+ sizeof(s64)) + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
u16 raw_data;
/* Commands to send for single conversion. */
u16 cnv_cmd;
@@ -660,9 +658,8 @@ static int ad4695_buffer_preenable(struct iio_dev *indio_dev)
iio_for_each_active_channel(indio_dev, bit) {
xfer = &st->buf_read_xfer[num_xfer];
xfer->bits_per_word = 16;
- xfer->rx_buf = &st->buf[rx_buf_offset];
+ xfer->rx_buf = &st->buf[rx_buf_offset++];
xfer->len = 2;
- rx_buf_offset += xfer->len;

if (bit == temp_chan_bit) {
temp_en = 1;

--
2.43.0