Messages in this thread | | | Date | Fri, 25 Feb 2022 00:41:27 -0800 | From | Guenter Roeck <> | Subject | Re: [PATCH v2 2/2] dt-bindings: hwmon: Add sample averaging property for ADM1275 |
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On 2/24/22 23:31, Krzysztof Kozlowski wrote: > On 25/02/2022 08:06, Krzysztof Kozlowski wrote: >> On 24/02/2022 16:43, Potin Lai wrote: >>> Add new properties for binding sample averaging in PMON_CONFIG register >>> >>> - adi,volt-curr-sample-average >>> - adi,power-sample-average >>> >>> Signed-off-by: Potin Lai <potin.lai@quantatw.com> >>> --- >>> .../bindings/hwmon/adi,adm1275.yaml | 44 +++++++++++++++++++ >>> 1 file changed, 44 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/hwmon/adi,adm1275.yaml b/Documentation/devicetree/bindings/hwmon/adi,adm1275.yaml >>> index 223393d7cafd..325f6827648f 100644 >>> --- a/Documentation/devicetree/bindings/hwmon/adi,adm1275.yaml >>> +++ b/Documentation/devicetree/bindings/hwmon/adi,adm1275.yaml >>> @@ -37,6 +37,48 @@ properties: >>> description: >>> Shunt resistor value in micro-Ohm. >>> >>> + adi,volt-curr-sample-average: >>> + description: | >>> + A value to configure VI_AVG in PMON_CONFIG register to indicate a >>> + number of samples to be used to report voltage and currentvalues. >> >> missing space after current. >> >>> + If set to 7, the 128 samples averaging would be used. >>> + >>> + $ref: /schemas/types.yaml#/definitions/uint8 >> >> Make it a uint32. >> >> The previous usage of this field was more appropriate. Instead of >> keeping register values in DT, it's better to keep logical value. What >> if in next cheap the register values have calculation method? >> >> This should be like in v1 - enum for number of samples to take in averaging. >> > > One more thought: this field could also stay in current approach if you > change the meaning from "value to configure VI_AVG" to something like > "the exponent used to determine the number of samples, where the base is 2". > > This approach would allow you to skip the "ilog" in the code. It sill > won't be that easily scalable if another chip comes with different > formula, but I think that's unlikely. >
The standard hwmon ABI expects the number of samples, it isn't always a power of 2, and the driver already implements it (with ilog2) as sysfs attribute. I don't really see the point of "optimizing" something like this to be chip specific just to avoid some error checking.
Guenter
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