[PATCH v6 01/11] iio: dac: mcp47feb02: initialize dac_data field in channel data struct at probe

[Ariana Lazar]

Prevent operations which use cache from overwriting default hardware values
with zeros by reading active DAC registers during probe to correctly
initialize the channel struct DAC values.

Fixes: bf394cc80369 ("iio: dac: adding support for Microchip MCP47FEB02")
Reported-by: sashiko-bot@xxxxxxxxxx
Link: https://lore.kernel.org/all/20260804134616.1D8A21F00A3E@xxxxxxxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ariana Lazar <ariana.lazar@xxxxxxxxxxxxx>
---
 drivers/iio/dac/mcp47feb02.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/dac/mcp47feb02.c b/drivers/iio/dac/mcp47feb02.c
index 8640b0ef4433da2b40d4b7e53fe6109737314951..6a3875e1d6a2c0cdd146410358130c44b1360f56 100644
--- a/drivers/iio/dac/mcp47feb02.c
+++ b/drivers/iio/dac/mcp47feb02.c
@@ -1019,7 +1019,12 @@ static int mcp47feb02_init_ctrl_regs(struct mcp47feb02_data *data)
 	gain_ch = gain_ch & MCP47FEB02_GAIN_BITS_MASK;
 	for_each_set_bit(i, &data->active_channels_mask, data->phys_channels) {
 		struct device *dev = regmap_get_device(data->regmap);
-		unsigned int pd_tmp;
+		unsigned int pd_tmp, dac_val;
+
+		ret = regmap_read(data->regmap, REG_ADDR(i), &dac_val);
+		if (ret)
+			return ret;
+		data->chdata[i].dac_data = dac_val;
 
 		data->chdata[i].ref_mode = (vref_ch >> (2 * i)) & MCP47FEB02_DAC_CTRL_MASK;
 		data->chdata[i].use_2x_gain = (gain_ch >> i)  & MCP47FEB02_GAIN_BIT_MASK;

-- 
2.43.0