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From:   Stephen Boyd <sboyd@kernel.org>
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Subject: RE: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array
Date:   Mon, 08 Oct 2018 00:40:51 -0700
Sender: linux-kernel-owner@vger.kernel.org
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Quoting Anson Huang (2018-09-03 00:20:53)
> > > 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 <xxx>"
> > > >>>> or "init-on-arrary=3D<xxx>"
> > > >>>> and enable those clocks?
> > > >>>
> > > >>> Parsing the clocks arrays from dtb is another way of enabling
> > > >>> critical 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, just 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 t=
o enable
> > 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
> > > >> registered by Linux, because there is no module in Linux side use
> > > >> it, it will shutdown the clock, which cause OP-TEE could not acces=
s the
> > device.
> > > >>
> > > >> Then people have to modify clk code to add CLK_IS_CRITICAL flag to
> > > >> make sure the clocks are not shutdown by Linux.
> > > >>
> > > >> However adding a new property in clk node and let driver code parse
> > > >> the dts, there is no need to modify clk driver code when OP-TEE ne=
eds
> > another device 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 fo=
rever?
> > >
> > > Sounds reasonable, but how could this be done without introducing
> > > platform-specific stuff in the OP-TEE driver?
> > >
> > =

> > Why is that a goal?
>  =

> I do NOT think we should consider such case in this patch series, whateve=
r OP-TEE needs for its own
> feature, it should do necessary operations either in its driver or somewh=
ere else by adding new patch.
> =


Why can't we add clks to the op-tee node in DT's /firmware container?
Then any clks in there can be turned on forever and left enabled by the
linux driver?