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From: Stephen Boyd <sboyd@kernel.org>
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Message-ID: <153573827629.93865.6200966443862432044@swboyd.mtv.corp.google.com>
Subject: Re: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array
Date: Fri, 31 Aug 2018 10:57:56 -0700
List-ID: <linux-clk.vger.kernel.org>

Quoting Jerome Forissier (2018-08-31 01:01:44)
> =

> =

> On 08/31/2018 03:29 AM, Stephen Boyd wrote:
> > Quoting Peng Fan (2018-08-12 18:15:41)
> >> Hi Anson,
> >>
> >>>>> -----Original Message-----
> >>>>> From: Anson Huang
> >>>>> Sent: 2018=E5=B9=B48=E6=9C=888=E6=97=A5 12:39
> >>>>> To: shawnguo@kernel.org; s.hauer@pengutronix.de;
> >>>>> kernel@pengutronix.de; Fabio Estevam <fabio.estevam@nxp.com>;
> >>>>> mturquette@baylibre.com; sboyd@kernel.org;
> >>>>> linux-arm-kernel@lists.infradead.org;
> >>>>> linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org
> >>>>> Cc: dl-linux-imx <linux-imx@nxp.com>
> >>>>> Subject: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array
> >>>>>
> >>>>> Clock framework will enable those clocks registered with
> >>>>> CLK_IS_CRITICAL flag, so no need to have clks_init_on array during
> >>>>> clock
> >>>> initialization now.
> >>>>
> >>>> Will it be more flexible to parse dts saying "critical-clocks =3D <x=
xx>"
> >>>> or "init-on-arrary=3D<xxx>"
> >>>> and enable those clocks?
> >>>
> >>> Parsing the clocks arrays from dtb is another way of enabling critica=
l clocks, but
> >>> for current i.MX6/7 platforms, we implement it in same way as most of=
 other
> >>> SoCs, currently I did NOT see any necessity of putting them in dtb, j=
ust adding
> >>> flag during clock registering is more simple, if there is any special=
 requirement
> >>> for different clocks set to be enabled, then we can add support to en=
able the
> >>> method of parsing critical-clocks from dtb. Just my two cents.
> >>
> >> Thinking about OP-TEE want to use one device, but it's clocks are regi=
stered
> >> by Linux, because there is no module in Linux side use it, it will shu=
tdown the clock,
> >> which cause OP-TEE could not access the device.
> >>
> >> Then people have to modify clk code to add CLK_IS_CRITICAL flag to mak=
e sure
> >> the clocks are not shutdown by Linux.
> >>
> >> However adding a new property in clk node and let driver code parse th=
e dts,
> >> there is no need to modify clk driver code when OP-TEE needs another d=
evice clock.
> >>
> > =

> > If OP-TEE needs linux to keep things on then why can't the OP-TEE driver
> > in Linux probe, acquire clocks, and keep the clks enabled forever?
> =

> Sounds reasonable, but how could this be done without introducing
> platform-specific stuff in the OP-TEE driver?
> =


Why is that a goal?