[PATCH v2 11/13] iio: pressure: mprls0025pa: stricter checks for the status byte

Petre Rodan
2026-01-14T10:07:53Z

Make sure a valid conversion comes with a status byte that only has
the MPR_ST_POWER bit set.
Return -EBUSY if also MPR_ST_BUSY is set or -EIO otherwise.

Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
---
v1 -> v2 no change
---
drivers/iio/pressure/mprls0025pa.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/pressure/mprls0025pa.c b/drivers/iio/pressure/mprls0025pa.c
index e4651d3f686d..078d1d719023 100644
--- a/drivers/iio/pressure/mprls0025pa.c
+++ b/drivers/iio/pressure/mprls0025pa.c
@@ -198,9 +198,10 @@ static void mpr_reset(struct mpr_data *data)
*
* Context: The function can sleep and data->lock should be held when calling it
* Return:
- * * 0 - OK, the pressure value could be read
- * * -ETIMEDOUT - Timeout while waiting for the EOC interrupt or busy flag is
- * still set after nloops attempts of reading
+ * * 0 - OK, the pressure value could be read
+ * * -EBUSY - Sensor does not have a new conversion ready
+ * * -ETIMEDOUT - Timeout while waiting for the EOC interrupt
+ * * -EIO - Invalid status byte received from sensor
*/
static int mpr_read_pressure(struct mpr_data *data, s32 *press)
{
@@ -253,10 +254,25 @@ static int mpr_read_pressure(struct mpr_data *data, s32 *press)
if (ret < 0)
return ret;

- if (data->rx_buf[0] & MPR_ST_ERR_FLAG) {
+ /*
+ * Status byte flags
+ * bit7 SANITY_CHK - must always be 0
+ * bit6 MPR_ST_POWER - 1 if device is powered
+ * bit5 MPR_ST_BUSY - 1 if device has no new conversion ready
+ * bit4 SANITY_CHK - must always be 0
+ * bit3 SANITY_CHK - must always be 0
+ * bit2 MEMORY_ERR - 1 if integrity test has failed
+ * bit1 SANITY_CHK - must always be 0
+ * bit0 MATH_ERR - 1 during internal math saturation error
+ */
+
+ if (data->rx_buf[0] == (MPR_ST_POWER | MPR_ST_BUSY))
+ return -EBUSY;
+
+ if (data->rx_buf[0] != MPR_ST_POWER) {
dev_err(data->dev,
- "unexpected status byte %02x\n", data->rx_buf[0]);
- return -ETIMEDOUT;
+ "unexpected status byte 0x%02x\n", data->rx_buf[0]);
+ return -EIO;
}

*press = get_unaligned_be24(&data->rx_buf[1]);

--
2.52.0