[PATCH 0/2] iio: humidity: si7020: Check device property for skipping reset in probe

[PATCH 0/2] iio: humidity: si7020: Check device property for skipping reset in probe

[Eddie James]

I2C commands issued after the SI7020 is starting up or after reset
can potentially upset the startup sequence. Therefore, the host
needs to wait for the startup sequence to finish before issuing
further i2c commands. This is impractical in cases where the SI7020
is on a shared bus or behind a mux, which may switch channels at
any time (generating I2C traffic). Therefore, check for a device
property that indicates that the driver should skip resetting the
device when probing.

Eddie James (2):
  dt-bindings: iio: humidity: Add si7020 bindings
  iio: humidity: si7020: Check device property for skipping reset in probe

 .../bindings/iio/humidity/silabs,si7020.yaml  | 42 +++++++++++++++++++
 drivers/iio/humidity/si7020.c                 | 14 ++++---
 2 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml

-- 
2.27.0

[PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Eddie James]

Document the si7020 bindings with a new "silabs,skip-reset" property.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 .../bindings/iio/humidity/silabs,si7020.yaml  | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml

diff --git a/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
new file mode 100644
index 000000000000..ab53bb8d9606
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/humidity/silabs,si7020.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SI7020 humidity + temperature sensor
+
+maintainers:
+  - David Barksdale <dbarksdale@uplogix.com>
+
+description: |
+   The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
+   are i2c devices which have an identical programming interface for
+   measuring relative humidity and temperature.
+
+properties:
+  compatible:
+    const: silabs,si7020
+
+  reg:
+    maxItems: 1
+
+  siliabs,skip-reset:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      Disables resetting of the device during probe
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    si7021-a20@40 {
+        silabs,skip-reset;
+        compatible = "silabs,si7020";
+        reg = <0x40>;
+    };
+...
-- 
2.27.0

Re: [PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Eddie James]

On 5/11/22 14:08, Eddie James wrote:
> Document the si7020 bindings with a new "silabs,skip-reset" property.


I missed the entry in trivial-devices.txt. I can push a v2 or a separate 
patch for that.

Eddie


>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
>   .../bindings/iio/humidity/silabs,si7020.yaml  | 42 +++++++++++++++++++
>   1 file changed, 42 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
>
> diff --git a/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> new file mode 100644
> index 000000000000..ab53bb8d9606
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> @@ -0,0 +1,42 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/humidity/silabs,si7020.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SI7020 humidity + temperature sensor
> +
> +maintainers:
> +  - David Barksdale <dbarksdale@uplogix.com>
> +
> +description: |
> +   The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
> +   are i2c devices which have an identical programming interface for
> +   measuring relative humidity and temperature.
> +
> +properties:
> +  compatible:
> +    const: silabs,si7020
> +
> +  reg:
> +    maxItems: 1
> +
> +  siliabs,skip-reset:
> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:
> +      Disables resetting of the device during probe
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    si7021-a20@40 {
> +        silabs,skip-reset;
> +        compatible = "silabs,si7020";
> +        reg = <0x40>;
> +    };
> +...

Re: [PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Krzysztof Kozlowski]

On 12/05/2022 00:08, Eddie James wrote:
> 
> On 5/11/22 14:08, Eddie James wrote:
>> Document the si7020 bindings with a new "silabs,skip-reset" property.
> 
> 
> I missed the entry in trivial-devices.txt. I can push a v2 or a separate 
> patch for that.

In this patch, please. Anyway you need v2.

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Rob Herring]

On Wed, 11 May 2022 14:08:34 -0500, Eddie James wrote:
> Document the si7020 bindings with a new "silabs,skip-reset" property.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
>  .../bindings/iio/humidity/silabs,si7020.yaml  | 42 +++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dts:21.13-26: Warning (reg_format): /example-0/si7021-a20@40:reg: property has invalid length (4 bytes) (#address-cells == 1, #size-cells == 1)
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: Warning (pci_device_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: Warning (pci_device_bus_num): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: Warning (simple_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: Warning (i2c_bus_reg): Failed prerequisite 'reg_format'
Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: Warning (spi_bus_reg): Failed prerequisite 'reg_format'
/builds/robherring/linux-dt-review/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: example-0: si7021-a20@40:reg:0: [64] is too short
	From schema: /usr/local/lib/python3.10/dist-packages/dtschema/schemas/reg.yaml
/builds/robherring/linux-dt-review/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: si7021-a20@40: 'silabs,skip-reset' does not match any of the regexes: 'pinctrl-[0-9]+'
	From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
/builds/robherring/linux-dt-review/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.example.dtb: si7021-a20@40: 'silabs,skip-reset' does not match any of the regexes: 'pinctrl-[0-9]+'
	From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/trivial-devices.yaml

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Krzysztof Kozlowski]

On 11/05/2022 21:08, Eddie James wrote:
> Document the si7020 bindings with a new "silabs,skip-reset" property.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>

Thank you for your patch. There is something to discuss/improve.

> ---
>  .../bindings/iio/humidity/silabs,si7020.yaml  | 42 +++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> new file mode 100644
> index 000000000000..ab53bb8d9606
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml
> @@ -0,0 +1,42 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/humidity/silabs,si7020.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SI7020 humidity + temperature sensor
> +
> +maintainers:
> +  - David Barksdale <dbarksdale@uplogix.com>
> +
> +description: |
> +   The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
> +   are i2c devices which have an identical programming interface for
> +   measuring relative humidity and temperature.
> +
> +properties:
> +  compatible:
> +    const: silabs,si7020
> +
> +  reg:
> +    maxItems: 1
> +
> +  siliabs,skip-reset:

Do not describe implementation (driver) behavior, but the device hardware.

> +    $ref: /schemas/types.yaml#/definitions/flag

"type:boolean" is shorter

> +    description:
> +      Disables resetting of the device during probe
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    si7021-a20@40 {

Generic node name, so "sensor"?

> +        silabs,skip-reset;
> +        compatible = "silabs,si7020";
> +        reg = <0x40>;

Order the properties: 1. compatible, 2. reg, then the rest.

> +    };
> +...


Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: iio: humidity: Add si7020 bindings

[Krzysztof Kozlowski]

On 11/05/2022 21:08, Eddie James wrote:
> Document the si7020 bindings with a new "silabs,skip-reset" property.
> +examples:
> +  - |
> +    si7021-a20@40 {
> +        silabs,skip-reset;
> +        compatible = "silabs,si7020";
> +        reg = <0x40>;
> +    };

As Rob's bot pointed out - you need to test your bindings. See
writing-schema.rst. Don't send bindings which do not work.


Best regards,
Krzysztof

[PATCH 2/2] iio: humidity: si7020: Check device property for skipping reset in probe

[Eddie James]

I2C commands issued after the SI7020 is starting up or after reset
can potentially upset the startup sequence. Therefore, the host
needs to wait for the startup sequence to finish before issuing
further i2c commands. This is impractical in cases where the SI7020
is on a shared bus or behind a mux, which may switch channels at
any time (generating I2C traffic). Therefore, check for a device
property that indicates that the driver should skip resetting the
device when probing.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 drivers/iio/humidity/si7020.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c
index ab6537f136ba..49f6a1b1f5c4 100644
--- a/drivers/iio/humidity/si7020.c
+++ b/drivers/iio/humidity/si7020.c
@@ -115,12 +115,14 @@ static int si7020_probe(struct i2c_client *client,
 				     I2C_FUNC_SMBUS_READ_WORD_DATA))
 		return -EOPNOTSUPP;
 
-	/* Reset device, loads default settings. */
-	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
-	if (ret < 0)
-		return ret;
-	/* Wait the maximum power-up time after software reset. */
-	msleep(15);
+	if (!device_property_read_bool(&client->dev, "silabs,skip-reset")) {
+		/* Reset device, loads default settings. */
+		ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
+		if (ret < 0)
+			return ret;
+		/* Wait the maximum power-up time after software reset. */
+		msleep(15);
+	}
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
-- 
2.27.0