Messages in this thread | | | From | Anson Huang <> | Subject | RE: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array | Date | Mon, 8 Oct 2018 08:34:59 +0000 |
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Anson Huang Best Regards!
> -----Original Message----- > From: Stephen Boyd <sboyd@kernel.org> > Sent: Monday, October 8, 2018 3:41 PM > To: kernel@pengutronix.de; linux-arm-kernel@lists.infradead.org; > linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org; > mturquette@baylibre.com; s.hauer@pengutronix.de; shawnguo@kernel.org; > Anson Huang <anson.huang@nxp.com>; Fabio Estevam > <fabio.estevam@nxp.com>; Jerome Forissier <jerome.forissier@linaro.org>; > Peng Fan <peng.fan@nxp.com>; Rob Herring <robh@kernel.org> > Cc: dl-linux-imx <linux-imx@nxp.com> > Subject: RE: [PATCH 2/2] clk: imx: imx7d: remove clks_init_on array > > 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年8月8日 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 = <xxx>" > > > > >>>> or "init-on-arrary=<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 operations > 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? And I think if op-tee has such requirement, can we have another patch to cover it? I believe all other i.MX platforms also have same requirements if considering op-tee support, so I think it should be another topic, what do you think?
Anson.
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