iio: adc: ad7606: fix serial register access

Fix register read/write routine as per datasheet.

When reading multiple consecutive registers, only the first one is read
properly. This is due to missing chip select deassert and assert again
between first and second 16bit transfer, as shown in the datasheet
AD7606C-16, rev 0, figure 110.

Fixes: f2a22e1e172f ("iio: adc: ad7606: Add support for software mode for ad7616")
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
Link: https://patch.msgid.link/20250418-wip-bl-ad7606-fix-reg-access-v3-1-d5eeb440c738@baylibre.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
index 885bf0b68e7775c5f4a12dfb827f502d5f782e8c..179115e909888b78330ee37b857ba6e355411055 100644 (file)
--- a/drivers/iio/adc/ad7606_spi.c
+++ b/drivers/iio/adc/ad7606_spi.c
@@ -131,7 +131,7 @@ static int ad7606_spi_reg_read(struct ad7606_state *st, unsigned int addr)
                {
                        .tx_buf = &st->d16[0],
                        .len = 2,
-                       .cs_change = 0,
+                       .cs_change = 1,
                }, {
                        .rx_buf = &st->d16[1],
                        .len = 2,