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Date:   Mon, 2 Aug 2021 09:45:58 +0100
From:   Lee Jones <lee.jones@linaro.org>
To:     Alistair Francis <alistair23@gmail.com>
Cc:     Alistair Francis <alistair@alistair23.me>,
        Rob Herring <robh+dt@kernel.org>, lgirdwood@gmail.com,
        Mark Brown <broonie@kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        Sascha Hauer <kernel@pengutronix.de>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 2/5] mfd: sy7636a: Initial commit
Message-ID: <YQewxp9UKpgmWF6Z@google.com>
References: <20210615103400.946-1-alistair@alistair23.me>
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On Wed, 28 Jul 2021, Alistair Francis wrote:

> On Thu, Jul 8, 2021 at 10:47 PM Lee Jones <lee.jones@linaro.org> wrote:
> >
> > On Thu, 08 Jul 2021, Alistair Francis wrote:
> >
> > > On Thu, Jun 17, 2021 at 7:20 PM Lee Jones <lee.jones@linaro.org> wrote:
> > > >
> > > > On Thu, 17 Jun 2021, Alistair Francis wrote:
> > > >
> > > > > On Wed, Jun 16, 2021 at 8:56 PM Lee Jones <lee.jones@linaro.org> wrote:
> > > > > >
> > > > > > On Tue, 15 Jun 2021, Alistair Francis wrote:
> > > > > >
> > > > > > > Initial support for the Silergy SY7636A Power Management chip.
> > > > > > >
> > > > > > > Signed-off-by: Alistair Francis <alistair@alistair23.me>
> > > > > > > ---
> > > > > > >  drivers/mfd/Kconfig         |  9 ++++
> > > > > > >  drivers/mfd/Makefile        |  1 +
> > > > > > >  drivers/mfd/sy7636a.c       | 82 +++++++++++++++++++++++++++++++++++++
> > > > > > >  include/linux/mfd/sy7636a.h | 47 +++++++++++++++++++++
> > > > > > >  4 files changed, 139 insertions(+)
> > > > > > >  create mode 100644 drivers/mfd/sy7636a.c
> > > > > > >  create mode 100644 include/linux/mfd/sy7636a.h
> > > > > > >
> > > > > > > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > > > > > > index 5c7f2b100191..7d6cf32b1549 100644
> > > > > > > --- a/drivers/mfd/Kconfig
> > > > > > > +++ b/drivers/mfd/Kconfig
> > > > > > > @@ -1339,6 +1339,15 @@ config MFD_SYSCON
> > > > > > >         Select this option to enable accessing system control registers
> > > > > > >         via regmap.
> > > > > > >
> > > > > > > +config MFD_SY7636A
> > > > > > > +     tristate "Silergy SY7636A Power Management chip"
> > > > > > > +     select MFD_CORE
> > > > > > > +     select REGMAP_I2C
> > > > > > > +     depends on I2C
> > > > > > > +     help
> > > > > > > +       Select this option to enable support for the Silergy SY7636A
> > > > > > > +       Power Management chip.
> > > > > > > +
> > > > > > >  config MFD_DAVINCI_VOICECODEC
> > > > > > >       tristate
> > > > > > >       select MFD_CORE
> > > > > > > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > > > > > > index 4f6d2b8a5f76..f95e1e725a95 100644
> > > > > > > --- a/drivers/mfd/Makefile
> > > > > > > +++ b/drivers/mfd/Makefile
> > > > > > > @@ -265,6 +265,7 @@ obj-$(CONFIG_MFD_STMFX)   += stmfx.o
> > > > > > >  obj-$(CONFIG_MFD_KHADAS_MCU)         += khadas-mcu.o
> > > > > > >  obj-$(CONFIG_MFD_ACER_A500_EC)       += acer-ec-a500.o
> > > > > > >
> > > > > > > +obj-$(CONFIG_MFD_SY7636A)    += sy7636a.o
> > > > > > >  obj-$(CONFIG_SGI_MFD_IOC3)   += ioc3.o
> > > > > > >  obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)     += simple-mfd-i2c.o
> > > > > > >  obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o
> > > > > > > diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c
> > > > > > > new file mode 100644
> > > > > > > index 000000000000..e08f29ea63f8
> > > > > > > --- /dev/null
> > > > > > > +++ b/drivers/mfd/sy7636a.c
> > > > > > > @@ -0,0 +1,82 @@
> > > > > > > +// SPDX-License-Identifier: GPL-2.0+
> > > > > > > +//
> > > > > >
> > > > > > Only the SPDX with C++ style comments please.
> > > > > >
> > > > > > > +// MFD parent driver for SY7636A chip
> > > > > >
> > > > > > Drop the MFD part.  It's a Linuxisum that doesn't really exist.
> > > > > >
> > > > > > > +// Copyright (C) 2021 reMarkable AS - http://www.remarkable.com/
> > > > > > > +//
> > > > > > > +// Authors: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
> > > > > > > +//          Alistair Francis <alistair@alistair23.me>
> > > > > > > +//
> > > > > > > +// Based on the lp87565 driver by Keerthy <j-keerthy@ti.com>
> > > > > > > +
> > > > > > > +#include <linux/interrupt.h>
> > > > > > > +#include <linux/mfd/core.h>
> > > > > > > +#include <linux/module.h>
> > > > > > > +#include <linux/of_device.h>
> > > > > > > +
> > > > > > > +#include <linux/mfd/sy7636a.h>
> > > > > > > +
> > > > > > > +static const struct regmap_config sy7636a_regmap_config = {
> > > > > > > +     .reg_bits = 8,
> > > > > > > +     .val_bits = 8,
> > > > > > > +};
> > > > > > > +
> > > > > > > +static const struct mfd_cell sy7636a_cells[] = {
> > > > > > > +     { .name = "sy7636a-regulator", },
> > > > > > > +     { .name = "sy7636a-temperature", },
> > > > > > > +     { .name = "sy7636a-thermal", },
> > > > > > > +};
> > > > > > > +
> > > > > > > +static const struct of_device_id of_sy7636a_match_table[] = {
> > > > > > > +     { .compatible = "silergy,sy7636a", },
> > > > > > > +     {}
> > > > > > > +};
> > > > > > > +MODULE_DEVICE_TABLE(of, of_sy7636a_match_table);
> > > > > >
> > > > > > Hold on.  This driver doesn't really do anything.  If you create OF
> > > > > > nodes for all the sub-devices, you can use simple-mfd-i2c.
> > > > > >
> > > > > > Any reason you can't do that?
> > > > >
> > > > > Just to confirm, you mean something like this?
> > > > >
> > > > > diff --git a/arch/arm/boot/dts/imx7d-remarkable2.dts
> > > > > b/arch/arm/boot/dts/imx7d-remarkable2.dts
> > > > > index 9327d1c06c96..3577104b3853 100644
> > > > > --- a/arch/arm/boot/dts/imx7d-remarkable2.dts
> > > > > +++ b/arch/arm/boot/dts/imx7d-remarkable2.dts
> > > > > @@ -382,6 +382,21 @@ epd_pmic: sy7636a@62 {
> > > > >                 pinctrl-0 = <&pinctrl_epdpmic>;
> > > > >                 #thermal-sensor-cells = <0>;
> > > > >
> > > > > +               regulator@0 {
> > > > > +                       compatible = "sy7636a-regulator";
> > > > > +                       reg = <0>;
> > > > > +               };
> > > > > +
> > > > > +               temperature@0 {
> > > > > +                       compatible = "sy7636a-temperature";
> > > > > +                       reg = <0>;
> > > > > +               };
> > > > > +
> > > > > +               thermal@0 {
> > > > > +                       compatible = "sy7636a-thermal";
> > > > > +                       reg = <0>;
> > > > > +               };
> > > > > +
> > > > >                 regulators {
> > > > >                         compatible = "silergy,sy7636a-regulator";
> > > > > diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
> > > > > index 87f684cff9a1..622a05318cff 100644
> > > > > --- a/drivers/mfd/simple-mfd-i2c.c
> > > > > +++ b/drivers/mfd/simple-mfd-i2c.c
> > > > > @@ -39,6 +39,7 @@ static int simple_mfd_i2c_probe(struct i2c_client *i2c)
> > > > >
> > > > >  static const struct of_device_id simple_mfd_i2c_of_match[] = {
> > > > >         { .compatible = "kontron,sl28cpld" },
> > > > > +       { .compatible = "silergy,sy7636a" },
> > > > >         {}
> > > > >  };
> > > > >  MODULE_DEVICE_TABLE(of, simple_mfd_i2c_of_match);
> > > >
> > > > Essentially.  Take a look at how the other users are implementing.
> > > >
> > > > The reg entries look bogus to me though.  Maybe just leave them out?
> > >
> > > So I tried this and didn't have any luck.
> > >
> > > After some Kconfig changes to allow it to build, I managed to get it
> > > probing, but I never got it to power up. It doesn't seem to be the
> > > same.
> >
> > I need a more technical reason why this is not the correct approach
> > for you.  "I can't get it to work" doesn't quite reach the quality
> > line I'm afraid.
> 
> Yep, so one thing that we need that the simple-mfd-i2c doesn't do is
> the epd-pwr-good-gpios GPIO. This is a GPIO line from the mfd that the
> regulator uses.

Can this be obtained from anywhere else?

Like in the regulator driver for instance.

> > Did you try enabling the debug prints in of_platform_bus_create() and
> > friends to see if your devices are probing correctly?
> 
> I think I did, but I can have another look and see if I can get it working.
> 
> Alistair
> 
> >

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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