[PATCH v2] iio: humidity: ens210: Fix missing I2C functionality checks

[PATCH v2] iio: humidity: ens210: Fix missing I2C functionality checks

[Salah Triki]

The ENS210 driver uses SMBus transactions (such as byte, word, and block
data reads/writes) during the probe and measurement phases. However, the
initial functionality check only validated a subset of these capabilities,
which could lead to loading failures on adapters requiring SMBus
emulation or native-only controllers.

To ensure compatibility across a wide range of I2C adapters, modify the
functionality check to verify if the adapter supports the required native
operations or, failing that, supports the SMBus emulation layer.

Fixes: c524fbca672e ("iio: humidity: Add support for ENS210")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 drivers/iio/humidity/ens210.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/humidity/ens210.c b/drivers/iio/humidity/ens210.c
index 77418d97f30d..c722087bc188 100644
--- a/drivers/iio/humidity/ens210.c
+++ b/drivers/iio/humidity/ens210.c
@@ -202,9 +202,12 @@ static int ens210_probe(struct i2c_client *client)
 	int ret;
 
 	if (!i2c_check_functionality(client->adapter,
-				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
-				     I2C_FUNC_SMBUS_WRITE_BYTE |
-				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+				I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+				I2C_FUNC_SMBUS_WRITE_BYTE |
+				I2C_FUNC_SMBUS_READ_BYTE_DATA |
+				I2C_FUNC_SMBUS_READ_WORD_DATA |
+				I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
+			!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL)) {
 		return dev_err_probe(&client->dev, -EOPNOTSUPP,
 			"adapter does not support some i2c transactions\n");
 	}
-- 
2.43.0

Re: [PATCH v2] iio: humidity: ens210: Fix missing I2C functionality checks

[Maxwell Doose]

On Tue May 5, 2026 at 12:22 PM CDT, Salah Triki wrote:
> The ENS210 driver uses SMBus transactions (such as byte, word, and block
> data reads/writes) during the probe and measurement phases. However, the
> initial functionality check only validated a subset of these capabilities,
> which could lead to loading failures on adapters requiring SMBus
> emulation or native-only controllers.
>
> To ensure compatibility across a wide range of I2C adapters, modify the
> functionality check to verify if the adapter supports the required native
> operations or, failing that, supports the SMBus emulation layer.
>
> Fixes: c524fbca672e ("iio: humidity: Add support for ENS210")
> Signed-off-by: Salah Triki <salah.triki@gmail.com>
> ---
>  drivers/iio/humidity/ens210.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
[snip]
>  	if (!i2c_check_functionality(client->adapter,
> -				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> -				     I2C_FUNC_SMBUS_WRITE_BYTE |
> -				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> +				I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> +				I2C_FUNC_SMBUS_WRITE_BYTE |
> +				I2C_FUNC_SMBUS_READ_BYTE_DATA |
> +				I2C_FUNC_SMBUS_READ_WORD_DATA |
> +				I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
> +			!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL)) {
>  		return dev_err_probe(&client->dev, -EOPNOTSUPP,
>  			"adapter does not support some i2c transactions\n");
>  	}

This alignment doesn't look right. Probably should be something like:

  	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
				     I2C_FUNC_SMBUS_WRITE_BYTE |
				     I2C_FUNC_SMBUS_READ_BYTE_DATA |
				     I2C_FUNC_SMBUS_READ_WORD_DATA |
				     I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
 			             !i2c_check_functionality(client->adapter, 
							      I2C_FUNC_SMBUS_EMUL)) {

best regards,
max

Re: [PATCH v2] iio: humidity: ens210: Fix missing I2C functionality checks

[Andy Shevchenko]

On Tue, May 05, 2026 at 12:33:36PM -0500, Maxwell Doose wrote:
> On Tue May 5, 2026 at 12:22 PM CDT, Salah Triki wrote:

> [snip]

> >  	if (!i2c_check_functionality(client->adapter,
> > -				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> > -				     I2C_FUNC_SMBUS_WRITE_BYTE |
> > -				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> > +				I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> > +				I2C_FUNC_SMBUS_WRITE_BYTE |
> > +				I2C_FUNC_SMBUS_READ_BYTE_DATA |
> > +				I2C_FUNC_SMBUS_READ_WORD_DATA |
> > +				I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
> > +			!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL)) {
> >  		return dev_err_probe(&client->dev, -EOPNOTSUPP,
> >  			"adapter does not support some i2c transactions\n");
> >  	}
> 
> This alignment doesn't look right. Probably should be something like:

However the end result is wrong, this one...

>   	if (!i2c_check_functionality(client->adapter,
> 				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> 				     I2C_FUNC_SMBUS_WRITE_BYTE |
> 				     I2C_FUNC_SMBUS_READ_BYTE_DATA |
> 				     I2C_FUNC_SMBUS_READ_WORD_DATA |
> 				     I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
>  			             !i2c_check_functionality(client->adapter, 
> 							      I2C_FUNC_SMBUS_EMUL)) {

...is also wrong.

if (!i2c_check_functionality(client->adapter,
			     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
			     I2C_FUNC_SMBUS_WRITE_BYTE |
			     I2C_FUNC_SMBUS_READ_BYTE_DATA |
			     I2C_FUNC_SMBUS_READ_WORD_DATA |
			     I2C_FUNC_SMBUS_READ_I2C_BLOCK) &&
    !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_EMUL)) {

-- 
With Best Regards,
Andy Shevchenko