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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:   Fri, 12 Oct 2018 12:48:02 -0700
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Quoting Anson Huang (2018-10-08 01:34:59)
> > 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-clock=
s =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 to 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 access 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 needs
> > > > 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
> > forever?
> > > > >
> > > > > 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,
> > > whatever OP-TEE needs for its own feature, it should do necessary ope=
rations
> > either in its driver or somewhere 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?
>  =

> I did NOT run op-tee with Linux-next kernel before, can you advise more?

Neither have I, so I can't advise more.

> And I think if op-tee has such requirement,
> can we have another patch to cover it?

Yes.


> I believe all other i.MX platforms also have same
> requirements if considering op-tee support, so I think it should be anoth=
er topic, what do you think?
> =


I'm going to drop these patches from my review queue. Please resend them
and please include the op-tee patches too.