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Message-ID: <20251022075816-GYC1522542@gentoo.org>
Date: Wed, 22 Oct 2025 15:58:16 +0800
From: Yixun Lan <dlan@...too.org>
To: Andre Przywara <andre.przywara@....com>
Cc: Lee Jones <lee@...nel.org>, Chen-Yu Tsai <wens@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Samuel Holland <samuel@...lland.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] regulator: axp20x: add support for the AXP318W
Hi Andre,
On 01:47 Wed 22 Oct , Andre Przywara wrote:
> On Wed, 22 Oct 2025 08:14:20 +0800
> Yixun Lan <dlan@...too.org> wrote:
>
> Hi,
>
> thanks for having a look!
>
> > Hi Andre,
> >
> > On 12:20 Tue 21 Oct , Andre Przywara wrote:
> > > The X-Powers AXP318W is a typical PMIC from X-Powers, featuring nine
> > > DC/DC converters and 28 LDOs, on the regulator side.
> > >
> > > Describe the chip's voltage settings and switch registers, how the
> > > voltages are encoded, and connect this to the MFD device via its
> > > regulator ID.
> > > We use just "318" for the internal identifiers, for easier typing and
> > > less churn. If something else other than the "AXP318W" shows up, that's
> > > an easy change, externally visible strings carry the additional letter
> > > already.
> > >
> > > Signed-off-by: Andre Przywara <andre.przywara@....com>
> > > ---
> > > drivers/regulator/axp20x-regulator.c | 170 ++++++++++++++++++++++++++-
> > > include/linux/mfd/axp20x.h | 43 +++++++
> > > 2 files changed, 211 insertions(+), 2 deletions(-)
> > >
..
> > > +
> > > +static const struct linear_range axp318_dcdc8_ranges[] = {
> > > + REGULATOR_LINEAR_RANGE(500000, 0, 70, 10000),
> > > + REGULATOR_LINEAR_RANGE(1220000, 71, 102, 20000),
> > > + REGULATOR_LINEAR_RANGE(1900000, 103, 118, 100000),
> > > +};
> >
> > In the AXP318W datasheet, it says:
> > section 7.1 DCDC/LCO desgin
> > 8. DCDC6/7/8/9 only able to tune at two voltage ranges which are
> > <1.54v and >1.54v, the tuning voltage should not step cross 1.54v
> > (I translate the original doc into english)
>
> Thanks, I now read something similar in my Google translated copy of the
> datasheet. But I don't understand what this is supposed to mean? That
> exactly 1.54V does not work, so the value of 87 is invalid? But any
> other value can be set?
I did a hard chinese - english translation..
No, I think it's probably a mistake that if user interpret value 87 as invalid,
from my understanding, DCDC6-9 only able to tune the voltage in two ranges:
(if user need to adjust the voltage dynamically)
a) range 0.5v - 1.54v (probably include 1.54v)
b) range 1.54v - 1.9v (probably also include 1.54v)
but can not tune in this case, example from range 1.5v - 1.6v which will
cross 1.54v point
I don't understand the logic behind but guess it's up to the HW/SoC
restriction in the design perspective..
>
> >
> > so, with this restricition, should we split the range into two?
> > one is dcdc6_lo_range, another dcdc6_hi_range
> >
> > or what do you think?
> >
> > ..
> > > + AXP_DESC(AXP318, ELDO1, "eldo1", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO1_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL3, BIT(6)),
> > > + AXP_DESC(AXP318, ELDO2, "eldo2", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO2_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL3, BIT(7)),
> > > + AXP_DESC(AXP318, ELDO3, "eldo3", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO3_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL4, BIT(0)),
> > > + AXP_DESC(AXP318, ELDO4, "eldo4", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO4_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL4, BIT(1)),
> > > + AXP_DESC(AXP318, ELDO5, "eldo5", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO5_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL4, BIT(2)),
> > > + AXP_DESC(AXP318, ELDO6, "eldo6", "eldoin", 500, 1500, 25,
> > > + AXP318_ELDO6_CONTROL, AXP318_ELDO_V_OUT_MASK,
> > > + AXP318_LDO_OUTPUT_CONTROL4, BIT(3)),
> >
> > also, in section 7.1 DCDC/LCO desgin
> > 3. ELDOIN can use DCDC's output as the voltage input, once in this case,
> > the LDO (output?) config voltage should lower than DCDC input voltage.
> >
> > Note: ELDOIN can use PS(Power Supply, should be equal to DCIN) or DCDC as input
> >
> > in case of Radxa A7A (A733) board, it use DCDC9 as ELDOIN,
> > Should we do something in the driver level? or leave up to user
>
> "User" really means board vendor here, right? As the actual board
could be user from software level perspective, who use or design this
> user is not meant to adjust those voltages anyway, and any range
> limitations should be considered during the board design phase.
I'd be fine if push these up to designer, and blame them for wrong usage
> So yes, DCDC9 is at 1.24V on the Radxa, and ELDOIN is connected to
> that, but only ELDO1 and ELDO6 are used, and they are fixed to 900mV
> and 800mV, respectively, and connected to SoC pins that require exactly
> those voltages. So there is no room for change or to adjust things
> here, and the requirements are met.
for this single case, right, we shouldn't worry about..
> If board designers/people ignore that, that it just won't work, and
> they get to keep the pieces. Nothing the driver can do here.
>
from a driver level, at least we can emit an error message to alert
user of the wrong voltage value set..
> Cheers,
> Andre
>
--
Yixun Lan (dlan)
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