[PATCH] iio: light: vcnl4035: Fix reversed ALS mode bit

[PATCH] iio: light: vcnl4035: Fix reversed ALS mode bit

[Alexander Sarmanow]

According to the datasheet (table 2) the ALS_SD bit behaves the opposite
way the current ALS mode defines are set, writing 0 powers the sensor
and writing 1 shuts it down.

The current driver thinks the ALS is up while it's actually shut down
and it's down when the systems powers it up.

Fixes: 55707294c4eb ("iio: light: Add support for vishay vcnl4035")
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Sarmanow <as@discnull.de>
---
Tested on a Raspberry Pi 3B+ with a VCNL4035 on I2C, running Raspberry
Pi OS downstream kernel 6.18.50. Checked with i2cget that bit 0 of the
config register 0x00 is 0 while PM runtime resume and 1 once it's
runtime suspended. Also builds cleanly against iio/testing.

 drivers/iio/light/vcnl4035.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/light/vcnl4035.c b/drivers/iio/light/vcnl4035.c
index ce1bd42b0c7c..f1cc75245001 100644
--- a/drivers/iio/light/vcnl4035.c
+++ b/drivers/iio/light/vcnl4035.c
@@ -44,8 +44,8 @@
 #define VCNL4035_DEV_ID_MASK		GENMASK(7, 0)
 
 /* Default values */
-#define VCNL4035_MODE_ALS_ENABLE	BIT(0)
-#define VCNL4035_MODE_ALS_DISABLE	0x00
+#define VCNL4035_MODE_ALS_ENABLE	0x00
+#define VCNL4035_MODE_ALS_DISABLE	BIT(0)
 #define VCNL4035_MODE_ALS_INT_ENABLE	BIT(1)
 #define VCNL4035_MODE_ALS_INT_DISABLE	0
 #define VCNL4035_DEV_ID_VAL		0x80

base-commit: a22dc7ebb21a6bd4c8b63bc2c1dd46a24945aae7

Best regards,
Alexander
-- 
2.47.3

Re: [PATCH] iio: light: vcnl4035: Fix reversed ALS mode bit

[Nuno Sá]

On Mon, Oct 12, 2026 at 04:43:15PM +0200, Alexander Sarmanow wrote:
> According to the datasheet (table 2) the ALS_SD bit behaves the opposite
> way the current ALS mode defines are set, writing 0 powers the sensor
> and writing 1 shuts it down.
> 
> The current driver thinks the ALS is up while it's actually shut down
> and it's down when the systems powers it up.
> 
> Fixes: 55707294c4eb ("iio: light: Add support for vishay vcnl4035")
> Cc: stable@vger.kernel.org
> Signed-off-by: Alexander Sarmanow <as@discnull.de>
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

> Tested on a Raspberry Pi 3B+ with a VCNL4035 on I2C, running Raspberry
> Pi OS downstream kernel 6.18.50. Checked with i2cget that bit 0 of the
> config register 0x00 is 0 while PM runtime resume and 1 once it's
> runtime suspended. Also builds cleanly against iio/testing.
> 
>  drivers/iio/light/vcnl4035.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/light/vcnl4035.c b/drivers/iio/light/vcnl4035.c
> index ce1bd42b0c7c..f1cc75245001 100644
> --- a/drivers/iio/light/vcnl4035.c
> +++ b/drivers/iio/light/vcnl4035.c
> @@ -44,8 +44,8 @@
>  #define VCNL4035_DEV_ID_MASK		GENMASK(7, 0)
>  
>  /* Default values */
> -#define VCNL4035_MODE_ALS_ENABLE	BIT(0)
> -#define VCNL4035_MODE_ALS_DISABLE	0x00
> +#define VCNL4035_MODE_ALS_ENABLE	0x00
> +#define VCNL4035_MODE_ALS_DISABLE	BIT(0)
>  #define VCNL4035_MODE_ALS_INT_ENABLE	BIT(1)
>  #define VCNL4035_MODE_ALS_INT_DISABLE	0
>  #define VCNL4035_DEV_ID_VAL		0x80
> 
> base-commit: a22dc7ebb21a6bd4c8b63bc2c1dd46a24945aae7
> 
> Best regards,
> Alexander
> -- 
> 2.47.3
> 

Re: [PATCH] iio: light: vcnl4035: Fix reversed ALS mode bit

[Jonathan Cameron]

On Mon, 12 Oct 2026 16:51:05 +0100
Nuno Sá <nuno.sa@analog.com> wrote:

> On Mon, Oct 12, 2026 at 04:43:15PM +0200, Alexander Sarmanow wrote:
> > According to the datasheet (table 2) the ALS_SD bit behaves the opposite
> > way the current ALS mode defines are set, writing 0 powers the sensor
> > and writing 1 shuts it down.
> > 
> > The current driver thinks the ALS is up while it's actually shut down
> > and it's down when the systems powers it up.
> > 
> > Fixes: 55707294c4eb ("iio: light: Add support for vishay vcnl4035")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Alexander Sarmanow <as@discnull.de>
> > ---  
> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Mystifying how this worked for original contributor.  Maybe it's one of
those last minute edits that went wrong.

Anyhow, applied and marked for stable as what you have matches the datasheet
and you've tested it so it's not an issue with a wrong datasheet.

Thanks,
Jonathan

> 
> > Tested on a Raspberry Pi 3B+ with a VCNL4035 on I2C, running Raspberry
> > Pi OS downstream kernel 6.18.50. Checked with i2cget that bit 0 of the
> > config register 0x00 is 0 while PM runtime resume and 1 once it's
> > runtime suspended. Also builds cleanly against iio/testing.
> > 
> >  drivers/iio/light/vcnl4035.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/iio/light/vcnl4035.c b/drivers/iio/light/vcnl4035.c
> > index ce1bd42b0c7c..f1cc75245001 100644
> > --- a/drivers/iio/light/vcnl4035.c
> > +++ b/drivers/iio/light/vcnl4035.c
> > @@ -44,8 +44,8 @@
> >  #define VCNL4035_DEV_ID_MASK		GENMASK(7, 0)
> >  
> >  /* Default values */
> > -#define VCNL4035_MODE_ALS_ENABLE	BIT(0)
> > -#define VCNL4035_MODE_ALS_DISABLE	0x00
> > +#define VCNL4035_MODE_ALS_ENABLE	0x00
> > +#define VCNL4035_MODE_ALS_DISABLE	BIT(0)
> >  #define VCNL4035_MODE_ALS_INT_ENABLE	BIT(1)
> >  #define VCNL4035_MODE_ALS_INT_DISABLE	0
> >  #define VCNL4035_DEV_ID_VAL		0x80
> > 
> > base-commit: a22dc7ebb21a6bd4c8b63bc2c1dd46a24945aae7
> > 
> > Best regards,
> > Alexander
> > -- 
> > 2.47.3
> >   

Re: [PATCH] iio: light: vcnl4035: Fix reversed ALS mode bit

[Alexander Sarmanow]

On Sun, Oct 18, 2026 at 12:28:22AM +0100, Jonathan Cameron wrote:
> Mystifying how this worked for original contributor.  Maybe it's one of
> those last minute edits that went wrong.

I can imagine that during the time the system powers the ALS down, the
actual sensor keeps measuring and writing to their internal buffer. The
moment of a drivers read it will get the recent sample with "just" a
delay resulting from runtime pm settings. That delay is probably not very
noticeable in practice. I think that way nobody noticed it.

Thank you,
Alexander