Re: [PATCH v3 2/5] mfd: sec: Add support for S2MPS15 PMIC

[Alim Akhtar]

On 10/28/2015 07:21 PM, Lee Jones wrote:
> On Wed, 28 Oct 2015, Krzysztof Kozlowski wrote:
>
> > W dniu 28.10.2015 o 17:46, Lee Jones pisze:
> > > On Wed, 28 Oct 2015, Krzysztof Kozlowski wrote:
> > >
> > > > On 26.10.2015 23:34, Lee Jones wrote:
> > > > > On Mon, 26 Oct 2015, Alim Akhtar wrote:
> > > > >
> > > > > > From: Thomas Abraham <thomas.ab@xxxxxxxxxxx>
> > > > > >
> > > > > > Add support for S2MPS15 PMIC which is similar to S2MPS11 PMIC. The S2MPS15
> > > > > > PMIC supports 27 LDO regulators, 10 buck regulators, RTC, three 32.768KHz
> > > > > > clock outputs and battery charger. This patch adds initial support for
> > > > > > LDO and buck regulators of S2MPS15 device.
> > > > > >
> > > > > > Signed-off-by: Thomas Abraham <thomas.ab@xxxxxxxxxxx>
> > > > > > Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
> > > > > > [Alim: Added s2mps15_devs like rtc and clk and related changes]
> > > > > > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> > > > > > ---
> > > > > >   drivers/mfd/sec-core.c              |   31 +++++++
> > > > > >   drivers/mfd/sec-irq.c               |    8 ++
> > > > > >   include/linux/mfd/samsung/core.h    |    1 +
> > > > > >   include/linux/mfd/samsung/s2mps15.h |  158 +++++++++++++++++++++++++++++++++++
> > > > > >   4 files changed, 198 insertions(+)
> > > > > >   create mode 100644 include/linux/mfd/samsung/s2mps15.h
> > > > >
> > > > > I replied to the previous set and won't be reviewing this one until
> > > > > all of the open points are solved.
> > > >
> > > > The naming and compatibles used by the driver are confusing but how it
> > > > was at beginning. Beside the confusion, the names are correct:
> > > >
> > > > 1. Main mfd driver:
> > > >   - compatible: samsung,s2mps1*-pmic
> > > >   - driver name: sec_pmic
> > > >
> > > > 2. Regulator driver:
> > > >   - no compatible (because it always searches for "regulators" subnode of
> > > > its parent... that is the convention/legacy behaviour)
> > > >   - driver name: s2mps1*-pmic
> > > >
> > > > I hope that explains your concerns.
> > >
> > > It explains *why*, but doesn't ease my concerns in any way.
> > >
> > > Unfortunately I've only just realised the disparity we have between
> > > MFD and the Regulator subsystem, which is annoying because it's now
> > > almost impossible to rectify.
> > >
> > > We should have taken one of two views.  Either a) The MFD is the PMIC
> > > device which encompasses regulator control.  In which case the MFD
> > > and it's corresponding compatible string would be named *-pmic and the
> > > regulator driver would be called *-regulator. Or b) The MFD could be
> > > considered a normal MFD and be named after the model number, then the
> > > regulator 'could' be named *-pmic.
> > >
> > > However, with reference to b), how much other Power Management does
> > > the regulator driver do besides control regulators?  I suspect not
> > > much.  Therefore my preference would be for a).  My second choice
> > > would be a mixuture of the two where nothing gets named *-pmic.  The
> > > last option on my list would be the current situation where we seem to
> > > be calling both the MFD (PMIC) itself and the Regulator driver
> > > *-pmic, which is not good.
> >
> > Starting from the description of device-family. This is called "Power
> > Management IC" but it is rather a "Power Deliver/Distribute IC". There
> > isn't any logic inside except enable/disable/configure/set low power
> > mode for regulators.
> >
> > However in the same time the IC comes (always) with:
> >   - 32kHz clocks,
> >   - RTC,
> >   - backup battery charger (no driver for it),
> >   - reset for SoC,
> >   - shutdown on thermal alert (also no driver for this control).
> >
> > The solution a) seems fine to me. Make sense and it looks entirely
> > backward compatible - only driver names will be modified.
>
> Perfect solution from my PoV.
>
> Thanks Krzysztof.
Thanks Jones/Krzysztof as always.
Will update the patches.


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