[PATCH v6 02/11] iio: dac: mcp47feb02: Fix gain field initialization for active channels

[Ariana Lazar]

As per MCP47FXBX48 Datasheet, in the format of the Gain Control and System
Status Register each DAC channel has one bit to control its gain,
starting at bit 8, while bits 0-7 contain status or unimplemented bits.

The previous formula didn't initialize correctly all channels, being
replaced by using field_get() with the already defined macro used in write
operations where needed in the rest of the driver implementation.
DAC_GAIN_MASK(i) extracts the gain control bit for each active channel
correctly in one step.

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 | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/iio/dac/mcp47feb02.c b/drivers/iio/dac/mcp47feb02.c
index 6a3875e1d6a2c0cdd146410358130c44b1360f56..fa4bd1df954844da35a8496758489189aeceb60d 100644
--- a/drivers/iio/dac/mcp47feb02.c
+++ b/drivers/iio/dac/mcp47feb02.c
@@ -1016,7 +1016,6 @@ static int mcp47feb02_init_ctrl_regs(struct mcp47feb02_data *data)
 	if (ret)
 		return ret;
 
-	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, dac_val;
@@ -1027,7 +1026,7 @@ static int mcp47feb02_init_ctrl_regs(struct mcp47feb02_data *data)
 		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;
+		data->chdata[i].use_2x_gain = field_get(DAC_GAIN_MASK(i), gain_ch);
 
 		/*
 		 * Inform the user that the current voltage reference read from the volatile

-- 
2.43.0