[PATCH v5 2/8] iio: light: si1133: prevent race condition on timeout

[Joshua Crofts via B4 Relay]

From: Joshua Crofts <joshua.crofts1@xxxxxxxxx>

Sashiko reported a bug where the si1133_command exits on timeout
without halting the sensor or masking the interrupt. If the sensor
completes the command later, any subsequent command to the sensor
will cause the IRQ handler to complete immediately, returning stale
data to the driver all while the command hasn't finished yet, shifting
all potential reads in the future.

Fix this by masking the IRQ if wait_for_completion_timeout() fails.
When initiating a new command, do a dummy read of the IRQ_STATUS
register and turn the IRQ back on.

Fixes: e01e7eaf37d8 ("iio: light: introduce si1133")
Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
Closes: https://sashiko.dev/#/message/20260428-si1133-checkup-v2-5-70ad14bfefe2%40gmail.com
Assisted-by: gemini:gemini-3.1-pro-preview
Signed-off-by: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
---
 drivers/iio/light/si1133.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/light/si1133.c b/drivers/iio/light/si1133.c
index c88c79202be2e21abb72067426e31b6bf97c61cf..bf7bf0f1631d49a1d04b89f172646e4afaf46438 100644
--- a/drivers/iio/light/si1133.c
+++ b/drivers/iio/light/si1133.c
@@ -395,8 +395,14 @@ static int si1133_command(struct si1133_data *data, u8 cmd)
 
 	expected_seq = (data->rsp_seq + 1) & SI1133_MAX_CMD_CTR;
 
-	if (cmd == SI1133_CMD_FORCE)
+	if (cmd == SI1133_CMD_FORCE) {
+		/* Flush pending IRQs from a previous timeout. */
+		regmap_read(data->regmap, SI1133_REG_IRQ_STATUS, &resp);
+		regmap_write(data->regmap, SI1133_REG_IRQ_ENABLE,
+			     SI1133_IRQ_CHANNEL_ENABLE);
+
 		reinit_completion(&data->completion);
+	}
 
 	err = regmap_write(data->regmap, SI1133_REG_COMMAND, cmd);
 	if (err) {
@@ -409,6 +415,7 @@ static int si1133_command(struct si1133_data *data, u8 cmd)
 		/* wait for irq */
 		if (!wait_for_completion_timeout(&data->completion,
 			msecs_to_jiffies(SI1133_COMPLETION_TIMEOUT_MS))) {
+			regmap_write(data->regmap, SI1133_REG_IRQ_ENABLE, 0);
 			err = -ETIMEDOUT;
 			goto out;
 		}

-- 
2.47.3