Re: [PATCH 07/12] iio: pressure: rohm-bm1390: Fix AVE_NUM initialization
From: Matti Vaittinen
Date: Mon Aug 17 2026 - 01:52:20 EST
On 17/08/2026 04:12, Jonathan Cameron wrote:
On Mon, 10 Aug 2026 10:53:07 +0300
Matti Vaittinen <matti.vaittinen@xxxxxxxxx> wrote:
From: Matti Vaittinen <mazziesaccount@xxxxxxxxx>FIELD_PREP(BM1390_MASK_AVE_NUM, BM1390_IIR_AVE_NUM));
The BM1390 tries to initialize the AVE_NUM to 110b at the start-up. The
field location is not taken into account, and value is written unsifted.
This causes the AVE_NUM to be initialized to zero.
Use FIELD_PREP() to shift the intended AVE_NUM value to correct field.
Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
Fixes: 81ca5979b6ed ("iio: pressure: Support ROHM BU1390")
---
drivers/iio/pressure/rohm-bm1390.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/pressure/rohm-bm1390.c b/drivers/iio/pressure/rohm-bm1390.c
index d00d7ed54cb1..29454570f257 100644
--- a/drivers/iio/pressure/rohm-bm1390.c
+++ b/drivers/iio/pressure/rohm-bm1390.c
@@ -479,6 +479,7 @@ static const struct iio_info bm1390_info = {
static int bm1390_chip_init(struct bm1390_data *data)
{
+ u8 regval;
int ret;
ret = regmap_write_bits(data->regmap, BM1390_REG_POWER,
@@ -512,8 +513,9 @@ static int bm1390_chip_init(struct bm1390_data *data)
* Default to use IIR filter in "middle" mode. Also the AVE_NUM must
* be fixed when IIR is in use.
*/
+ regval = FIELD_PREP(BM1390_MASK_AVE_NUM, BM1390_IIR_AVE_NUM);
ret = regmap_update_bits(data->regmap, BM1390_REG_MODE_CTRL,
- BM1390_MASK_AVE_NUM, BM1390_IIR_AVE_NUM);
+ BM1390_MASK_AVE_NUM,
If respining I would drop the local variable and just go a bit long on the line.
I like the mask to be clearly visible in both parameters and a local variable
prevents that. Fine if the line is really long, but it's only about 83 chars here.
I am not going to insist - but I will explain my view - which will sound like insisting XD
For me it is always a tad harder to read code when function or macro "calls" are done inside a parameter list. Hence I like a local variable here. I do 100% agree with you that mask (and sometimes raw numbers) should be visible in code - and not hidden into variables / defines. Still, in this case, the mask is assigned to the variable right above the line it gets used. So, I could argue the mask is still pretty visible, and FIELD_PREP() is called on it's own line and not inside the regmap_update_bits() parameter list - which is more readable for me.
Well, if you feel strongly about the variable - then I can ditch it. 83 chars is still okay(ish) - even on my "old eyes, big font and 3 terminals in parallel" -display setup ;)
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
~~ When things go utterly wrong vim users can always type :help! ~~