On 06/23/2013 02:54 PM, Lars-Peter Clausen wrote: > On 06/22/2013 03:28 PM, Alexandre Belloni wrote: >> On 22/06/2013 15:20, Lars-Peter Clausen wrote: >>> On 06/22/2013 03:07 PM, Alexandre Belloni wrote: >>>> On 22/06/2013 14:02, Lars-Peter Clausen wrote: >>>>> On 06/22/2013 01:55 PM, Jonathan Cameron wrote: >>>>>> On 06/20/2013 07:57 PM, Alexandre Belloni wrote: >>>>>>> The Nuvoton NAU7802 ADC is a 24-bit 2-channels I2C ADC, with adjustable >>>>>>> gain and sampling rates. >>>>>>> >>>>>> Sorry, somewhat low on time today so only a quick review. >>>>>> >>>>>> 1) Missing userspace ABI documentation. Also, perhaps min_conversions is >>>>>> a little vague? Not that I have a better idea! >>>>> I really don't like the name min_conversions either. Isn't this effectively >>>>> a decimation filter? >>>> Yeah, it could be seen like that but it is only relevant and only >>>> happens when switching between channels. I'm open to any ideas. >>>> >>> I see. Is there anything about this in the datasheet on how many conversions >>> you usually need? Is this really something you need to change at runtime or >>> does moving this to platform data work? >>> >>> >> >> There is actually nothing in the datasheet. The default value (6 >> conversions) was found experimentally. What I did was saturating the ADC >> with the higher value on one channel and the lower value on the other >> one and I tried to find when reading both channel sequentially was >> resulting in a correct value. >> >> You may not need to change it at runtime. And that value mainly depend >> on the precision versus speed balance you want to achieve. If you know >> that the values on both channels will not be to far apart, then you may >> not need to wait at all. >> >> Would you think that is something I should hide in the DT ? Or maybe I >> can drop that knob for now and see if it is needed in the future. >> > > It is always a good idea to be conservative when introducing new ABI, so if > you think we can get away with hardcoding this in the driver I think that's > a good idea. > I agree entirely. We can always make it controllable later as long as we keep the default the same as the value you hard code in now. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
