Re: [PATCH 3/9] mfd: mt6397: Split MediaTek MT6366 PMIC out of MT6358

[AngeloGioacchino Del Regno]

Il 04/08/23 05:47, Chen-Yu Tsai ha scritto:
> On Thu, Aug 3, 2023 at 5:01 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
> > Il 03/08/23 09:42, Chen-Yu Tsai ha scritto:
> > > The MT6366 PMIC is mostly, but not fully, compatible with MT6358. It has
> > > a different set of regulators. Specifically, it lacks the camera related
> > > VCAM* LDOs, but has additional VM18, VMDDR, and VSRAM_CORE LDOs.
> > >
> > > Add a separate compatible for the MT6366 PMIC. The regulator cell for
> > > this new entry uses a new compatible string matching MT6366.
> > >
> > > Fixes: c47383f84909 ("mfd: Add support for the MediaTek MT6366 PMIC")
> > > Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
> >
> > I agree in that the LDOs are a bit different, but that's handled by the
> > mt6358-regulator driver regardless of the actual devicetree compatible,
> > as that's selected through a chip_id check.
> >
> > Finally, looking at the driver implementation itself, the addition of a
> > specific mt6366 compatible here seems redundant, because the actual HW is
> >    - Handled by drivers, but
> >    - Described by bindings
> >
> > Any other opinions on this?
>
> Well, on the bindings side, we can't have MT6366 fall back to MT6358,
> neither for the whole PMIC nor just for the regulators. For the latter
> it's because neither is a subset of the other, which a) makes them not
> fallback compatible as required by the spirit of fallback compatibles,
> and b) cannot be described with a fallback compatible, as the fallback
> one will have properties/nodes that are not valid for the other, and
> vice versa.
>
> Without a fallback compatible to lean in for the regulator driver, we
> will need to split out the compatible at the mfd level as well. AFAIU
> the mfd core matches mfd-cells based on the compatible strings it is
> given in the driver.

Hmm... you might actually be right on this.
But! I just want to be sure that we're doing things the right way.. and
I'd like to get an opinion from a bindings person, as I think that's the
most appropriate thing that can be done.

Krzysztof, please, can you check this one?

Thanks!
Angelo

> ChenYu
>
> > Regards,
> > Angelo
> >
> > > ---
> > >    drivers/mfd/mt6397-core.c | 31 +++++++++++++++++++++++++++++++
> > >    1 file changed, 31 insertions(+)
> > >
> > > diff --git a/drivers/mfd/mt6397-core.c b/drivers/mfd/mt6397-core.c
> > > index f6c1f80f94a4..3f8dfe60a59b 100644
> > > --- a/drivers/mfd/mt6397-core.c
> > > +++ b/drivers/mfd/mt6397-core.c
> > > @@ -206,6 +206,26 @@ static const struct mfd_cell mt6359_devs[] = {
> > >        },
> > >    };
> > >
> > > +static const struct mfd_cell mt6366_devs[] = {
> > > +     {
> > > +             .name = "mt6358-regulator",
> > > +             .of_compatible = "mediatek,mt6366-regulator"
> > > +     }, {
> > > +             .name = "mt6358-rtc",
> > > +             .num_resources = ARRAY_SIZE(mt6358_rtc_resources),
> > > +             .resources = mt6358_rtc_resources,
> > > +             .of_compatible = "mediatek,mt6358-rtc",
> > > +     }, {
> > > +             .name = "mt6358-sound",
> > > +             .of_compatible = "mediatek,mt6358-sound"
> > > +     }, {
> > > +             .name = "mt6358-keys",
> > > +             .num_resources = ARRAY_SIZE(mt6358_keys_resources),
> > > +             .resources = mt6358_keys_resources,
> > > +             .of_compatible = "mediatek,mt6358-keys"
> > > +     },
> > > +};
> > > +
> > >    static const struct mfd_cell mt6397_devs[] = {
> > >        {
> > >                .name = "mt6397-rtc",
> > > @@ -280,6 +300,14 @@ static const struct chip_data mt6359_core = {
> > >        .irq_init = mt6358_irq_init,
> > >    };
> > >
> > > +static const struct chip_data mt6366_core = {
> > > +     .cid_addr = MT6358_SWCID,
> > > +     .cid_shift = 8,
> > > +     .cells = mt6366_devs,
> > > +     .cell_size = ARRAY_SIZE(mt6366_devs),
> > > +     .irq_init = mt6358_irq_init,
> > > +};
> > > +
> > >    static const struct chip_data mt6397_core = {
> > >        .cid_addr = MT6397_CID,
> > >        .cid_shift = 0,
> > > @@ -358,6 +386,9 @@ static const struct of_device_id mt6397_of_match[] = {
> > >        }, {
> > >                .compatible = "mediatek,mt6359",
> > >                .data = &mt6359_core,
> > > +     }, {
> > > +             .compatible = "mediatek,mt6366",
> > > +             .data = &mt6366_core,
> > >        }, {
> > >                .compatible = "mediatek,mt6397",
> > >                .data = &mt6397_core,