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. - Lars -- 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
