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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@arm.com" <sudeep.holla@arm.com>, "mturquette@baylibre.com"
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	<linux-arm-kernel@lists.infradead.org>, "linux-clk@vger.kernel.org"
	<linux-clk@vger.kernel.org>, "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>, Ranjani Vaidyanathan
	<ranjani.vaidyanathan@nxp.com>, Glen G Wienecke <glen.wienecke@nxp.com>,
	Nitin Garg <nitin.garg_3@nxp.com>, Chuck Cannon <chuck.cannon@nxp.com>
Subject: RE: [PATCH V2 2/2] clk: scmi: support state_ctrl_forbidden
Thread-Topic: [PATCH V2 2/2] clk: scmi: support state_ctrl_forbidden
Thread-Index: AQHaKO/hcegSzKiHwky3h5GWn2PoCLDTZMiAgACNREA=
Date: Thu, 11 Jan 2024 00:07:30 +0000
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References: <20231207093345.581048-1-peng.fan@oss.nxp.com>
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> Subject: Re: [PATCH V2 2/2] clk: scmi: support state_ctrl_forbidden
>=20
> On Thu, Dec 07, 2023 at 05:33:45PM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > Some clocks may exported to linux, while those clocks are not allowed
> > to configure by Linux. For example:
> >
>=20
> Hi,
>=20
> > SYS_CLK1-----
> >              \
> > 	     --MUX--->MMC1_CLK
> >              /
> > SYS_CLK2-----
> >
> > MMC1 needs set parent, so SYS_CLK1 and SYS_CLK2 are exported to Linux,
> > then the clk propagation will touch SYS_CLK1 or SYS_CLK2.
> > So we need bypass the failure for SYS_CLK1 or SYS_CLK2 when enable the
> > clock of MMC1.
> >
>=20
>=20
> So I was puzzled a bit at first (as said) by the fact that here we silent=
ly swallow
> the failure if the SCMI Clock cannot be disabled, BUT then I spotted in
> include/linux/clk.h
>=20
> 	/**
> 	 * clk_enable - inform the system when the clock source should be
> running.
> 	 * @clk: clock source
> 	 *
> 	 * If the clock can not be enabled/disabled, this should return success.
>=20
> ...so I suppose it is fine for the CLK framework at the end.
>=20
> My next remaining question is why are you not doing the same when (ret =
=3D=3D -
> EACCES && clk->info->state_ctrl_forbidden) for atomic_ops ?
>=20
> I.e. in:
>=20
> 	clk-scmi.c::static int scmi_clk_atomic_enable(struct clk_hw *hw)
>=20
> Any particular reason (beside not needing it in your particular case...)

No particular reason, we not use atomic_ops in our case. So I am not able
to test it. I could add the same in atomic_ops in V3.

Thanks,
Peng.
>=20
> Thanks,
> Cristian