On Wed, Sep 7, 2022 at 1:34 PM Tim Hardisty <t...@jti.uk.com.invalid> wrote:
> On Wed, Sep 7, 2022 at 1:03 PM Tim Hardisty <t...@jti.uk.com.invalid> > wrote: > >> > >> > >> >>> Please correct me if I'm still missing something, as there > are zero > >> >>> clues I can find as to what each ops function (for example) > is > >> >>> actually supposed to do. > >> >> > >> >> > >> >> > >> >>Here is two examples: > >> >>https://github.com/apache/incubator- > >> >>nuttx/blob/master/drivers/power/supply/regulator_gpio.c > >> >>https://github.com/apache/incubator- > >> >>nuttx/blob/master/drivers/power/supply/regulator_rpmsg.c > >> > >> >thank you for these, I will take a look and hopefully they > will point me > >> >in the right direction. > >> > > Please: what are the purpose of: > >> > >> set_voltage_sel > >> get_voltage_sel > > > >This really should be documented in the definition of struct > >regulator_ops_s in include/nuttx/power/regulator.h, particularly what > >is the difference between set_voltage and set_voltage_sel. > > I agree - this should be there as comments. I will eventually submit a PR > for my driver and, if it's not done by then, I will add these in the same > PR Thank you! That will be much appreciated! >That said, based on reading the code at _regulator_do_set_voltage() in > >drivers/power/supply/regulator.c, it appears that: > > >1) set_voltage() is given a minimum and maximum desired voltage in > >microvolts and sets (if possible) the regulator's voltage selector to > >generate something between those bounds. It is up to the lower-half > >driver to look at the desired min and max voltage and figure out what > >the selector should be, whereas: > > >2) set_voltage_sel() is given the selector value itself and sets that. > >The lower-half driver doesn't make decisions in this case; the > >upper-half driver iterates through all available voltages to decide > >which one is the "best" and then calls the lower-half driver with that > >selector value. > > >The logic in _regulator_do_set_voltage() is such that if the > >lower-half driver provides set_voltage(), it prefers to call that; if > >not, then I assume it's a more "primitive" driver and therefore the > >upper-half decides the selector value. > > This is a great help, Nathan: thank you. The ACT8945A only allows discrete > voltages to be set (64 values) so the set_voltage_sel may one way to sort > this, although I already have code to select the right register value by > some mathematical shenigans so could put that in the lower half and make > use of the min and max values. I suppose you could do both, though I don't know whether that would just be a waste of code space. Perhaps internally one would call the other. It is all making sense now: lack of comments, and no examples in 10.3, are > what done me in. Glad to be of help! Comments--or rather GOOD comments--are invaluable! Cheers Nathan
