[PATCH v2 1/2] iio: dac: adi-axi-dac: fix bus read

[Angelo Dureghello]

From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>

Fix bus read function.

Testing the driver, on a random basis, wrong reads was detected, mainly
by a wrong DAC chip ID read at first boot.
Before reading the expected value from the AXI regmap, need always to
wait for busy flag to be cleared.

Fixes: e61d7178429a ("iio: dac: adi-axi-dac: extend features")
Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
---
 drivers/iio/dac/adi-axi-dac.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/iio/dac/adi-axi-dac.c b/drivers/iio/dac/adi-axi-dac.c
index 8ed5ad1fa24cef649056bc5f4ca80abbf28b9323..5ee077c58d7f9730aec8a9c9dff5b84108b3a47e 100644
--- a/drivers/iio/dac/adi-axi-dac.c
+++ b/drivers/iio/dac/adi-axi-dac.c
@@ -760,6 +760,7 @@ static int axi_dac_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val,
 {
 	struct axi_dac_state *st = iio_backend_get_priv(back);
 	int ret;
+	u32 ival;
 
 	guard(mutex)(&st->lock);
 
@@ -772,6 +773,13 @@ static int axi_dac_bus_reg_read(struct iio_backend *back, u32 reg, u32 *val,
 	if (ret)
 		return ret;
 
+	ret = regmap_read_poll_timeout(st->regmap,
+				AXI_DAC_UI_STATUS_REG, ival,
+				FIELD_GET(AXI_DAC_UI_STATUS_IF_BUSY, ival) == 0,
+				10, 100 * KILO);
+	if (ret)
+		return ret;
+
 	return regmap_read(st->regmap, AXI_DAC_CUSTOM_RD_REG, val);
 }
 

-- 
2.49.0