Re: sharpsl_pm: using milivolts instead of custom units?

[Richard Purdie <rpurdie@rpsys.net>]

On Fri, 2005-11-11 at 13:03 +0100, Pavel Machek wrote:
> Hi!
> 
> It seems to me that sharpsl.c is using some very custom units:
> 
> #define SHARPSL_CHARGE_ON_VOLT         0x99  /* 2.9V */
> #define SHARPSL_CHARGE_ON_TEMP         0xe0  /* 2.9V */
> #define SHARPSL_CHARGE_ON_ACIN_HIGH   0x9b  /* 6V */
> #define SHARPSL_CHARGE_ON_ACIN_LOW    0x34  /* 2V */
> #define SHARPSL_FATAL_ACIN_VOLT        182   /* 3.45V */
> #define SHARPSL_FATAL_NOACIN_VOLT      170   /* 3.40V */
> 
> ...what are they? Unfortunately collie uses very different units:

They're raw values as provided by the ADC. Collie will have a different
ADC and hence different raw values. There's no real need to convert them
to mV and back again all the time.

> #ifdef CONFIG_SA1100_COLLIE
> struct battery_thresh spitz_battery_levels_noac[] = {
>         { 368, 100},
>         { 358,  25},
>         { 356,   5},
>         {   0,   0},
> ...
> 
> ...so it could get very confusing. Would it be feasible to convert to
> mV as soon as possible and have all constants in milivolts? I realize
> they may be slightly different for different models, but they should
> at least be comparable.

The battery levels are totally different between the models and each is
going to need a levels translation table as its an extremely none linear
decay curve. Using ADC values here makes a lot of sense as that's as
granular as the information ever gets and you don't start to lose
accuracy anywhere with rounding.

I still think you've much bigger problems to worry about as this code is
heavily PXA biased and is going to need a lot of changes to work on the
SA1100. Its why I've put it in mach-pxa rather than common and a
separate driver for collie based on this code might be easier.

Richard