Re: [PATCH 1/7] dt-bindings: iio: adc: Add support for QCOM PMIC5 Gen4 ADC

[Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>]

Hi Krzysztof,

On 8/4/2026 1:50 PM, Krzysztof Kozlowski wrote:
> On Fri, Jul 31, 2026 at 11:36:14PM +0530, Jishnu Prakash wrote:
>> PMIC5 Gen4 ADC is similar to PMIC5 Gen3 ADC, with several changes made for
>> improved performance, mostly at the hardware level. The main differences are
>> increased ratiometric conversion resolution (from 14 bits to 16 bits) and
>> increased bit field width for PMIC SID (to allow communication with an
>> increased number of PMICs, supported on latest SoCs).
>>
>> Signed-off-by: Jishnu Prakash <jishnu.prakash@oss.qualcomm.com>
>> ---
>>  .../bindings/iio/adc/qcom,spmi-adc5-gen3.yaml      | 47 +++++++++++++++++++++-
>>  1 file changed, 46 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-adc5-gen3.yaml b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-adc5-gen3.yaml
>> index 149f4af8f4b8..e79ddc2acca0 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-adc5-gen3.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-adc5-gen3.yaml
>> @@ -21,9 +21,14 @@ description: |
>>    All boards using a particular (SOC + master PMIC) combination will have the
>>    same number of ADC SDAMs supported on that PMIC.
>>  
>> +  PMIC5 Gen4 ADC is similar to Gen3 ADC, with some differences such as
>> +  improved ratiometric conversion resolution.
>> +
>>  properties:
>>    compatible:
>> -    const: qcom,spmi-adc5-gen3
>> +    enum:
>> +      - qcom,spmi-adc5-gen3
>> +      - qcom,spmi-adc5-gen4
>>  
>>    reg:
>>      items:
>> @@ -83,6 +88,46 @@ patternProperties:
>>            This property indicates ADC_TM monitoring is done on this channel.
>>          type: boolean
>>  
>> +      qcom,adc5-gen4:
>> +        description:
>> +          Indicates channel is of type ADC5 Gen4. This may be needed in cases where the
>> +          master PMIC has an ADC peripheral of type Gen3, but some of the other PMICs it
>> +          communicates with have ADC peripherals of type Gen4, so channels of those PMICs
>> +          need to be marked as Gen4 to ensure their conversions are handled correctly.
>> +        type: boolean
> 
> It is implied by the compatibles, in this case the peripheral
> compatible.

This property is needed in cases where a Gen3 master PMIC has Gen4
channels under it.

The main point to keep in mind for Gen3/Gen4 ADC is that the compatible
describes the ADC peripheral on the master PMIC, but the master PMIC's
ADC communicates with ADCs on other PMICs, which may not always be of
the same generation. Under the master PMIC's ADC DT node, we have ADC
channel nodes from all the PMICs it communicates with.


For example, SM8750 has the following 8 PMICs, having ADC channels:

PMK8550 (Gen3 master PMIC)
PM8550
PM8550vs (2 instances)
PM8550ve (3 instances)
PMIH0108


ADCs on the first 7 PMICs are of type Gen3, but PMIH0108 has
Gen4 ADC. So ADC channels of PMIH0108 exposed under the PMK8550
ADC peripheral need to have the "qcom,adc5-gen4" property to
indicate they are of a different generation and may need a
different conversion formula.

Similarly, on some variants of the upcoming mobile platform Maili,
we have the opposite case (master PMIC has Gen4 ADC, one of the
other PMICs has Gen3 ADC), so we would also need the "qcom,adc5-gen3"
property for some platforms.

I'll add a description for these properties too in the commit
message, hope it helps.

Thanks,
Jishnu


> 
> Best regards,
> Krzysztof
>