Messages in this thread | | | Date | Mon, 6 Mar 2023 15:44:23 +0100 | From | Mike Looijmans <> | Subject | Re: [PATCH v4 2/2] iio: adc: Add TI ADS1100 and ADS1000 |
| |
Met vriendelijke groet / kind regards,
Mike Looijmans System Expert
TOPIC Embedded Products B.V. Materiaalweg 4, 5681 RJ Best The Netherlands
T: +31 (0) 499 33 69 69 E: mike.looijmans@topicproducts.com W: www.topic.nl
Please consider the environment before printing this e-mail On 06-03-2023 14:29, Andy Shevchenko wrote: > On Mon, Mar 06, 2023 at 02:13:12PM +0100, Mike Looijmans wrote: >> The ADS1100 is a 16-bit ADC (at 8 samples per second). >> The ADS1000 is similar, but has a fixed data rate. > ... > >> + microvolts = regulator_get_voltage(data->reg_vdd); >> + /* >> + * val2 is in 'micro' units, n = val2 / 1000000 >> + * result must be millivolts, d = microvolts / 1000 >> + * the full-scale value is d/n, corresponds to 2^15, >> + * hence the gain = (d / n) >> 15, factoring out the 1000 and moving the >> + * bitshift so everything fits in 32-bits yields this formula. >> + */ >> + gain = ((microvolts + BIT(14)) >> 15) * 1000 / val2; > Perhaps adding MICROVOLT_PER_MILLIVOLT (to units.h) and use it here?
Would that require a separate patch?
I fear that would get feedback like "why not MICROCOULOB_PER_MILLICOULOMB".
If I fill in the equation then that "1000" is actually MICROVOLT_PER_MICROVOLT_PER_MILLIVOLT, which would evaluate to simply "MILLIVOLT".
> > Besides that it's seems like > > microvolts = regulator_get_voltage(data->reg_vdd); > gain = DIV_ROUNDUP_CLOSEST(microvolts, BIT(15)) * > MICROVOLT_PER_MILLIVOLT / val2;
Yeah, the DIV_ROUNDUP_CLOSEST is more readable.
>> + if (gain <= 0 || gain > 8) >> + return -EINVAL; > As I commented out in the previous discussion (please, give a chance to the > reviewers to answer before issuing a new version of the series) this better > to be > > if (gain < BIT(0) || gain > BIT(3)) > > which will show the nature of power of two implicitly. > >> + regval = ffs(gain) - 1; >> + ads1100_set_config_bits(data, ADS1100_PGA_MASK, regval); > Can be unified in one line.
Combining it all, I'd arrive at this code:
gain = DIV_ROUNDUP_CLOSEST(microvolts, BIT(15)) * MILLI / val2; if (gain < BIT(0) || gain > BIT(3)) return -EINVAL;
ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
>> + return 0; >> +} > ... > >> + return ads1100_set_config_bits( >> + data, ADS1100_DR_MASK, >> + FIELD_PREP(ADS1100_DR_MASK, i)); > Wrong indentation. > Please, check all your code for this kind of issues. > I always run it through checkpatch.pl but that didn't report on this indentation.
A bit of digging in the scripts directory yields "Lindent". Feeding my file to that indeed changes those lines (and some others too). I'll run my next patch through that.
-- Mike Looijmans
| |