Messages in this thread | | | Date | Thu, 2 Nov 2023 10:17:15 -0700 | Subject | Re: [PATCH v4 2/2] rtc: max31335: add driver support | From | Guenter Roeck <> |
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On 11/2/23 09:57, Alexandre Belloni wrote: [ ... ] >>>> +static int max31335_read_offset(struct device *dev, long *offset) >>>> +{ >>>> + struct max31335_data *max31335 = dev_get_drvdata(dev); >>>> + u32 value; >>>> + int ret; >>>> + >>>> + ret = regmap_read(max31335->regmap, MAX31335_AGING_OFFSET, >>> &value); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + *offset = value; >>> >>> This is super dubious, what is the unit of MAX31335_AGING_OFFSET ? >>> >> >> There is not additional information on the AGING_OFFSET register (no >> other offset registers). >> I treated it as a raw value that user can write/read. Should I drop the >> offset implementation? >> > > The value exposed to userspace is in parts per billion. If you can't do > the conversion, then you have to drop it. >
The max31334 datasheet says "Resolution = 0.477ppm". Again, the datasheet for max31335 is not public, so it is impossible to say what the resolution is for that chip, but I would assume that it is documented.
Guenter
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