Re: [RFT][PATCH 1/2] regulator: as3722: Fix equation to calculatemax_uV in regulator_lin_range macro

[Laxman Dewangan]

On Wednesday 02 October 2013 05:26 PM, Axel Lin wrote:
> 2013/10/2 Laxman Dewangan <ldewangan@xxxxxxxxxx>:
> > On Tuesday 01 October 2013 09:03 PM, Axel Lin wrote:
> > > Fix off-by-one in the equation to calculate max_uV.
> > >
> > > Signed-off-by: Axel Lin <axel.lin@xxxxxxxxxx>
> > > ---
> > > Hi,
> > > I don't have the datasheet and h/w.
> > > Just found this issue while reading the code. (Only compile test).
> > >
> > > Axel
> > >    drivers/regulator/as3722-regulator.c | 2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/regulator/as3722-regulator.c
> > > b/drivers/regulator/as3722-regulator.c
> > > index 16a5d26..c6a1fc6 100644
> > > --- a/drivers/regulator/as3722-regulator.c
> > > +++ b/drivers/regulator/as3722-regulator.c
> > > @@ -441,7 +441,7 @@ static struct regulator_ops as3722_ldo3_extcntrl_ops =
> > > {
> > >                  .max_sel = _max_sel,                                    \
> > >                  .uV_step = _step_uV,                                    \
> > >                  .min_uV = _min_uV,                                      \
> > > -               .max_uV = _min_uV + (_max_sel - _min_sel + 1) * _step_uV,
> > > \
> > > +               .max_uV = _min_uV + (_max_sel - _min_sel) * _step_uV,   \
> > >          }
> > >      static const struct regulator_linear_range as3722_ldo_ranges[] = {
> > The datasheet says:
> >
> > The voltage select bits set the LDO output voltage 0.825V...3.3V, 25mV steps
> >    ....00h : LDO off
> >    01h-24h : V_LDO4=0.8V+ldo4_vsel*25mV
> >    25h-3Fh : do not use
> >    40h-7Fh : V_LDO4=1.725V+(ldo4_vsel-40h)*25mV
> >
> > And put the linear range as
> > regulator_lin_range(0x01, 0x24,  800000, 25000),
> > regulator_lin_range(0x40, 0x7F, 1725000, 25000),
> >
> >
> > So as per datasheet, value 0x24 is equal to 1700mV.
> >                                       and 0x7F equal to 3300
> >
> > I created equation based on first entry which is wrong for second entry and
> > your equation is correct for second entry but break first one.
> >
> > I think your equation is correct with following change:
> > regulator_lin_range(0x01, 0x24,  825000, 25000),
> Hi Laxman,
> Thanks for the review.
> And how about the setting for as3722_sd2345_ranges?
> How the datasheet says for sd2345?
>
> e.g. Should I change
> regulator_lin_range(0x01, 0x40,  600000, 12500),
> to
> regulator_lin_range(0x01, 0x40,  612500, 12500),

For this, it need to change for all entry:

The voltage select bits set the DC/DC output voltage level and power the 
DC/DC converter down.
  ....00h : DC/DC powered down
  01h-40h : V_SD2=0.6V+sd2_vsel*12.5mV
  41h-70h : V_SD2=1.4V+(sd2_vsel-40h)*25mV
  71h-7Fh : V_SD2=2.6V+(sd2_vsel-70h)*50mV

Again second and third entry need to be taken care.
Third entry min_uV is completely wrong here. Did not get caught in my 
testing as I did not have requirement of the third range in my board.

static const struct regulator_linear_range as3722_sd2345_ranges[] = {
        regulator_lin_range(0x01, 0x40,  600000, 12500),
        regulator_lin_range(0x41, 0x70, 1400000, 25000),
        regulator_lin_range(0x71, 0x7F, 1725000, 50000),
};


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