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From:   Peng Fan <peng.fan@nxp.com>
To:     Sascha Hauer <s.hauer@pengutronix.de>,
        "Peng Fan (OSS)" <peng.fan@oss.nxp.com>
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Subject: RE: [PATCH 1/2] dt-bindings: clock: imx8m: introduce
 fsl,protected-clocks property
Thread-Topic: [PATCH 1/2] dt-bindings: clock: imx8m: introduce
 fsl,protected-clocks property
Thread-Index: AQHYsFgAb9/Dm+cZSEyj68dAWhpa+K2v/VoAgAEfCpA=
Date:   Tue, 16 Aug 2022 07:13:27 +0000
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References: <20220815033632.1687854-1-peng.fan@oss.nxp.com>
 <20220815033632.1687854-2-peng.fan@oss.nxp.com>
 <20220815135756.GC17485@pengutronix.de>
In-Reply-To: <20220815135756.GC17485@pengutronix.de>
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Hi Sascha,

> Subject: Re: [PATCH 1/2] dt-bindings: clock: imx8m: introduce fsl,protect=
ed-
> clocks property
>=20
> Hi Peng,
>=20
> On Mon, Aug 15, 2022 at 11:36:31AM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > i.MX8M Linux run on top of Jailhouse hypervisor, the root cell Linux
> > should not disable clocks used by inmate. This would also benifit AMP
> > to avoid Linux disable clocks used by Cortex-M4/M7.
> >
> > So introduce fsl,protected-clocks for above case.
> >
> > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > ---
> >  Documentation/devicetree/bindings/clock/imx8m-clock.yaml | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> > b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> > index 458c7645ee68..0ec490ff9a09 100644
> > --- a/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> > +++ b/Documentation/devicetree/bindings/clock/imx8m-clock.yaml
> > @@ -39,6 +39,10 @@ properties:
> >        ID in its "clocks" phandle cell. See include/dt-bindings/clock/i=
mx8m-
> clock.h
> >        for the full list of i.MX8M clock IDs.
> >
> > +  fsl,protected-clocks:
> > +    description: List of the Protected clock.
> > +    $ref: /schemas/types.yaml#/definitions/uint32-array
>=20
> There already is a generic protected-clocks property described in
> https://eur01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fgithu
> b.com%2Fdevicetree-org%2Fdt-
> schema%2Fblob%2F0d1b78cd0c3d9a3d523ced17d7da64b03f6c18ea%2Fdtsc
> hema%2Fschemas%2Fclock%2Fclock.yaml%23L131&amp;data=3D05%7C01%7
> Cpeng.fan%40nxp.com%7C5dbc72639c9147765af208da7ec63315%7C686ea
> 1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637961686968811809%7CUn
> known%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI
> 6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=3DD%2BfJA5h
> wblaX8VH%2BdQoN0pEFmCipfZHHf0ZVo07B4kg%3D&amp;reserved=3D0
> We probably shouldn't add a property with the same name but different
> meaning.
>=20

Thanks for sharing the info. I should check the common bindings before
cook this patchset.

> I am not sure if we want to go the route of a fsl specific property, it l=
ooks
> like other SoCs could have similar problems and it might be worth solving
> this problem with a broader view.
>=20

I see qcom just drop the clock entries before registering the clocks. But t=
o
i.MX8M, it is not feasible to drop those clocks, unless check the
protected-clocks property before registering every clock. This is odd.

So here I just wanna let i.MX8M clk driver prepare enable the clocks listed
in protected-clocks property to avoid linux disable those clocks.
> Anyway, please add a description to the binding what this property actual=
ly
> does.
I will switch to use the common bindings.

Thanks,
Peng.
>=20
> Sascha
>=20
> --
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