Re: [PATCH V3 2/2] iio: adc: spmi-vadc: Changes to support different scaling

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Hi Stan,

On 27-Oct-16 4:48 PM, Stanimir Varbanov wrote:
Hi Rama,

On 10/26/2016 05:41 PM, Rama Krishna Phani A wrote:
Polling can also be used for End of conversion completion. Implement logic
to choose either polling or interrupt for End of conversion completion.
Scaling can be done on the voltage to report adc code in physical units.
Add changes to support different scale functions to convert adc code to
physical units.

Signed-off-by: Rama Krishna Phani A <rphani@xxxxxxxxxxxxxx>
---
 .../devicetree/bindings/iio/adc/qcom,spmi-vadc.txt |  14 ++
 drivers/iio/adc/qcom-spmi-vadc.c                   | 263 +++++++++++++++++----
 2 files changed, 236 insertions(+), 41 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
index 0fb4613..39e31c0e 100644
--- a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
@@ -37,6 +37,12 @@ VADC node:
     Value type: <prop-encoded-array>
     Definition: End of conversion interrupt.

+- qcom,vadc-poll-eoc:
+    Usage: optional
+    Value type: <bool>
+    Definition: Use polling instead of interrupts for End of Conversion
+		completion.

Why you need to add such a flag in DT?

The DT should describe hardware details not how the driver will choose
pooling vs interrupt.

On which use-case you would prefer pooling?


Few PMIC's support interrupt functionality for ADC where as few PMIC's dont support. Based on the functionality that is supported in hardware we choose whether to go for polling or for interrupt.

+
 Channel node properties:

 - reg:
@@ -92,6 +98,14 @@ Channel node properties:
             Valid values are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
             If property is not found, 1 sample will be used.

+- qcom,scale-function:
+    Usage: optional
+    Value type: <u32>
+    Definition: Scaling function used to convert raw ADC code to
+	units specific to a given channel. Scaled units can be
+	microvolts, millidegC.Valid values are: 0, 1, 2, 3, 4.
+	If property is not found, 0 scaling will be used.

This shouldn't be in DT binding. Just select the scale function for each
channel in the driver based on compatible property.


Ok ., Will remove this binding from DT, implement logic in driver and will post next patch.

Thanks,
Ramakrishna

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