Re: [PATCH-v2 2/2] regulator: 88pm800: Add support for configuration of dual phase on BUCK1

[Vaibhav Hiremath]

On Thursday 06 August 2015 05:28 AM, Krzysztof Kozlowski wrote:
> On 05.08.2015 17:45, Vaibhav Hiremath wrote:
> > On Thursday 23 July 2015 10:21 AM, Krzysztof Kozlowski wrote:
> > > 2015-07-22 1:23 GMT+09:00 Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>:
> > > > 88PM860 device supports dual phase mode on BUCK1 output.
> > > > In normal usecase, BUCK1A and BUCK1B operates independently with 3A
> > > > capacity. And they both can work as a dual phase providing 6A capacity.
> > > >
> > > > This patch updates the regulator driver to read the respective
> > > > DT property and enable dual-phase mode on BUCK1.
> > > >
> > > > Note that, this is init time (one time) initialization.
> >
> > Sorry for delayed response, was on bed rest almost for week.
> >
> > > > Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
> > > > ---
> > > >    drivers/regulator/88pm800.c | 31 +++++++++++++++++++++++++++++++
> > > >    include/linux/mfd/88pm80x.h |  3 +++
> > > >    2 files changed, 34 insertions(+)
> > >
> > > Don't you need to update the constraints also? I think the BUCK1
> > > regulator has fixed constraint of 3 A:
> > >     PM800_BUCK(buck1, BUCK1, BUCK_ENA, 0, 3000000, buck1_volt_range,
> > > 0x55),
> > > and now it can handle 6 A.
> >
> > Actually, BUCK1A and BUCK1B both combined together provide 6A capacity.
> > And as discussed earlier, we need board change for this.
> >
> > I am quite not sure.
>
> AFAIU the regulator driver creates one BUCK1 regulator with constraints
> 3 A. However after your change the regulator will handle up to 6 A.
>
> This means that constraints set by driver are wrong.
>
> Additionally I can't find BUCK1A and BUCK1B regulators. Driver provides
> only BUCK1.

My patch does add BUCK1A and BUCK1B, please refer to the PATCH[4/5] of
earlier series, which is accepted.

https://patchwork.kernel.org/patch/6810461/


> > Should I read the property and update the constraint runtime during
> > probe?
>
> Driver should provide real constraints. Find the proper way to do this.
>
> The pm800_regulator_info[] array is not const so you can change it in
> whatever way you want (although it should be const for existing driver
> because regulator core accepts const and passing it to driver_data is
> not necessary).


Probably that is the only way to handle this.

how about,

As you mentioned, pm800_regulator_info[] is not constant, so I can 
update the constraint before regulator_register() and also do not
register BUCK1B, if dual phase is enabled.

So in summary,

if (dual phase is enabled)
{
	Update constraint of BUCK1 to 6A
	and do not register BUCK1B
} else {
	register both BUCK1A and BUCK1B with default constraint of 3A.
}

Thanks,
Vaibhav
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