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

[Jishnu Prakash]

Hi Krzysztof,

On 8/6/2026 4:23 PM, Jishnu Prakash wrote:
> 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@xxxxxxxxxxxxxxxx>
>>> ---
>>>  .../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.
> 

Please let me know, does the above explanation look fine for
why we need the channel property "qcom,adc5-gen4" ?

And Jonathan was asking me to split this patch, to add the
new Gen4 compatible first and channel properties separately,
do you have any preferences there?

Thanks,
Jishnu


> Thanks,
> Jishnu
> 
> 
>>
>> Best regards,
>> Krzysztof
>>
>