Messages in this thread | | | Subject | Re: [PATCH v2] iio: adc: Add support for TI ADC1x8s102 | From | Jan Kiszka <> | Date | Wed, 3 May 2017 19:11:49 +0200 |
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On 2017-05-03 10:43, Andy Shevchenko wrote: > On Wed, May 3, 2017 at 11:24 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote: >> On 2017-05-03 10:06, Andy Shevchenko wrote: >>> On Wed, May 3, 2017 at 8:35 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote: >>>> On 2017-05-02 22:53, Andy Shevchenko wrote: > >>>>>> + ret = device_property_read_u32(&spi->dev, "ext-vin-microvolt", &val); >>>>> >>>>> Why not to read u16 here? >>>>> >>>> >>>> Can I read a property with arbitrary width? Then this would simplify >>>> things. >>> >>> device_property_read_u16(); >> >> By now I found out that ACPI does not care about the property type >> width, only DT does. So reading it as u16 under ACPI would be fine. But >> with DT, we will need a correctly sized property as well - default is u32. > > I'm a bit lost here. ACPI cares and DT cares about property size.
ACPI_TYPE_INTEGER, used for properties, is always stored and read as 64-bit value and then casted to the requested type.
In contrast, if you restrict a DT property via "/bits/ XX", its storage format changes, and you are better off using the correct access function for it. That's what I mean.
Jan
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