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From: Peng Fan <peng.fan@nxp.com>
To: Cristian Marussi <cristian.marussi@arm.com>, "Peng Fan (OSS)"
	<peng.fan@oss.nxp.com>
CC: Sudeep Holla <sudeep.holla@arm.com>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>, Conor Dooley <conor+dt@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>, Fabio Estevam
	<festevam@gmail.com>, Linus Walleij <linus.walleij@linaro.org>, Aisheng Dong
	<aisheng.dong@nxp.com>, Jacky Bai <ping.bai@nxp.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>, "devicetree@vger.kernel.org"
	<devicetree@vger.kernel.org>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>, "imx@lists.linux.dev" <imx@lists.linux.dev>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
Subject: RE: [PATCH v3 4/6] pinctrl: scmi: export pinctrl_scmi_get_pins
Thread-Topic: [PATCH v3 4/6] pinctrl: scmi: export pinctrl_scmi_get_pins
Thread-Index: AQHamSj4tA0oEn/LJ0GAeG40RoRvxrGCVjCAgAAAbEA=
Date: Wed, 1 May 2024 12:42:11 +0000
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References: <20240428-pinctrl-scmi-oem-v3-v3-0-eda341eb47ed@nxp.com>
 <20240428-pinctrl-scmi-oem-v3-v3-4-eda341eb47ed@nxp.com>
 <ZjI3abJUIgo4xgRu@pluto>
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> Subject: Re: [PATCH v3 4/6] pinctrl: scmi: export pinctrl_scmi_get_pins
>=20
> On Sun, Apr 28, 2024 at 01:07:50PM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > Add pinctrl-scmi.h to include the function prototype and 'struct
> > scmi_pinctrl' to export pinctrl_scmi_get_pins, so other drivers could
> > use it.
> >
>=20
> Hi Peng,
>=20
> so you wrote a new alternative SCMI driver using Pinctrl protocol@0x19 so
> that you can just parse you custom DT bindings and then use the SCMI
> pinctrl_ops to set the OEM extensions to configure your platform...
> ...since your firmware cannot cope with the all SCMI stack footprint....
>=20
> ... you seemed to have solved the issue of having 2 Pinctrl drivers coexi=
sting
> under the Linux Pinctrl subsystem while attached to the same
> protocol@19 node with patch 5/6 blocklist (if I get that right..)

Yes, right. With blocklist and allowlist, two drivers could coexist.

>=20
> I think this approach of a standalone SCMI alternative Pinctrl driver tha=
t
> handles distinctly NXP OEM extensions and DT-parsing is certainly more
> preferable than the original series you posted months ago where custom NX=
P
> stuff were simply stuck on top of the Generic SCMI Pinctrl driver...
>=20
> ...what I still dont understand is why you exported data and structure fr=
om
> pincttl-scmi.c to use it here; when NXP pinctrl is active the standard Li=
nux
> generic Pinctrl driver wont be alive, so not probed, so no data can be sh=
ared,
> the only thing I can imagine is that you are just trying to avoid duplica=
ting a
> dozen lines from the logic of
> scmi_pinctrl_get_pins() into your new NXP driver.

Yes, you are right, I just wanna avoid duplicating scmi_pinctrl_get_pins.

>=20
> In this way, though, you are creating a dependency between 2 drivers, tha=
t
> are not even allowed to cohexist at runtime really (due to the blocklist =
trick).
>=20
> Am I missing something ?

No, your understanding is correct.

>=20
> If not, I think it will be much better to just rewrite that few lines of
> scmi_pincrtrl_pins_get trivial logic into your NXP driver and keep the 2
> drivers fully distinct at all times.

ok. I could write the pinctrl-scmi-imx.c local get pins logic, not using
pinctrl-scmi.c to decouple the two drivers.

Thanks,
Peng
>=20
> Thanks,
> Cristian