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From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: "Rob Herring" <robh+dt@kernel.org>,
	"Jonathan Hunter" <jonathanh@nvidia.com>,
	"Ulf Hansson" <ulf.hansson@linaro.org>,
	"Viresh Kumar" <vireshk@kernel.org>,
	"Stephen Boyd" <sboyd@kernel.org>,
	"Peter De Schrijver" <pdeschrijver@nvidia.com>,
	"Mikko Perttunen" <mperttunen@nvidia.com>,
	"Peter Chen" <peter.chen@kernel.org>,
	"Mark Brown" <broonie@kernel.org>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Nishanth Menon" <nm@ti.com>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Lucas Stach" <dev@lynxeye.de>, "Stefan Agner" <stefan@agner.ch>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"Michael Turquette" <mturquette@baylibre.com>,
	linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-pm@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-staging@lists.linux.dev, linux-spi@vger.kernel.org,
	linux-pwm@vger.kernel.org, linux-mtd@lists.infradead.org,
	linux-mmc@vger.kernel.org, linux-media@vger.kernel.org,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
	linux-clk@vger.kernel.org
Subject: Re: [PATCH v8 06/34] dt-bindings: clock: tegra-car: Document new tegra-clocks sub-node
Date: Fri, 20 Aug 2021 05:51:35 +0300	[thread overview]
Message-ID: <cad7c578-f533-12f8-3dc0-d2854344148c@gmail.com> (raw)
In-Reply-To: <YR6HWMuYcF6NIepi@orome.fritz.box>

19.08.2021 19:31, Thierry Reding пишет:
>> The "device" representation is internal to the kernel. It's okay to me
>> to have PLLs represented by a device, it's a distinct h/w by itself.
>>
>> CCF supports managing of clock's RPM and it requires to have clock to be
>> backed by a device. That's what we are using here.
>>
>> Please see
>> https://elixir.bootlin.com/linux/v5.14-rc6/source/drivers/clk/clk.c#L109
> Looking at the implementation of __clk_register() and where that device
> pointer typically comes from, I don't think the way this is used here is
> what was intended. The way I interpret the code is that a clock is
> registered with a parent device (i.e. its provider) and
> clk_pm_runtime_get() is then used internally as a way to make sure that
> when a clock is prepared, it's parent device is runtime resumed. This is
> presumably to ensure that any registers that the driver might need to
> access in order to prepare and enable the clock are accessible (i.e. the
> CAR is not powered off or in reset).
> 
> So the struct device that is passed to __clk_register() (or its callers)
> should be that of the CAR rather than virtual struct devices created by
> the CAR.
> 
> And it's a bit debatable whether or not PLLs represent distinct
> hardware. Ultimately every transistor on a chip could be considered
> distinct hardware. But a platform device is a device on a platform bus,
> which is really just another way of saying it's a hardware block that's
> accessible from the CPU via a memory-mapped address. A PLL (just like
> other clocks) is merely a resource exposed by means of access to these
> registers. So I don't think they should be platform devices. Even making
> them struct device:s seems a bit of a stretch.
> 
> Is there any reason why struct clk can't be used for this? I mean, the
> whole purpose of that structure is to represent clocks. Why do we need
> to make them special?

Because we need to perform DVFS for PLLs. The only way to do it without
having to reinvent existing frameworks is to use these frameworks and
they require a device.

  parent reply	other threads:[~2021-08-20  2:51 UTC|newest]

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-17  1:27 [PATCH v8 00/34] NVIDIA Tegra power management patches for 5.16 Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 01/34] opp: Add dev_pm_opp_sync() helper Dmitry Osipenko
2021-08-17  7:55   ` Viresh Kumar
2021-08-17 15:49     ` Dmitry Osipenko
2021-08-18  3:55       ` Viresh Kumar
2021-08-18  4:12         ` Dmitry Osipenko
2021-08-18  4:29           ` Dmitry Osipenko
2021-08-18  4:30             ` Dmitry Osipenko
2021-08-18  4:34               ` Viresh Kumar
2021-08-18  4:31           ` Viresh Kumar
2021-08-18  4:37             ` Dmitry Osipenko
2021-08-18  4:53               ` Viresh Kumar
2021-08-18  5:21                 ` Dmitry Osipenko
2021-08-18  5:58                   ` Viresh Kumar
2021-08-18  6:00                     ` Viresh Kumar
2021-08-18  6:22                     ` Dmitry Osipenko
2021-08-18  6:27                       ` Viresh Kumar
2021-08-18  8:29                         ` Ulf Hansson
2021-08-18  9:14                           ` Viresh Kumar
2021-08-18  9:41                             ` Ulf Hansson
2021-08-18  9:42                               ` Ulf Hansson
2021-08-18  9:50                               ` Viresh Kumar
2021-08-18 10:08                                 ` Ulf Hansson
2021-08-18 15:43                                   ` Dmitry Osipenko
2021-08-18 15:46                                     ` Dmitry Osipenko
2021-08-19 13:07                                     ` Ulf Hansson
2021-08-19 19:35                                       ` Dmitry Osipenko
2021-08-20  5:07                                         ` Viresh Kumar
2021-08-20 12:42                                         ` Ulf Hansson
2021-08-21 17:34                                           ` Dmitry Osipenko
2021-08-23 10:46                                             ` Ulf Hansson
2021-08-23 15:54                                               ` Dmitry Osipenko
2021-08-18 15:55                               ` Dmitry Osipenko
2021-08-19  6:16                                 ` Viresh Kumar
2021-08-19 14:55                                   ` Ulf Hansson
2021-08-20  5:18                                     ` Viresh Kumar
2021-08-20 12:57                                       ` Ulf Hansson
2021-08-23 20:24                                         ` Dmitry Osipenko
2021-08-24  3:04                                           ` Viresh Kumar
2021-08-22 18:35                                       ` Dmitry Osipenko
2021-08-25 15:41                                         ` Dmitry Osipenko
2021-08-26  2:54                                           ` Viresh Kumar
2021-08-26  2:55                                             ` Viresh Kumar
2021-08-17  1:27 ` [PATCH v8 02/34] soc/tegra: pmc: Disable PMC state syncing Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 03/34] soc/tegra: Don't print error message when OPPs not available Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 04/34] soc/tegra: Add devm_tegra_core_dev_init_opp_table_simple() Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 05/34] soc/tegra: Use dev_pm_opp_sync() Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 06/34] dt-bindings: clock: tegra-car: Document new tegra-clocks sub-node Dmitry Osipenko
2021-08-18  1:15   ` Rob Herring
2021-08-18  1:44     ` Dmitry Osipenko
2021-08-18 13:52       ` Thierry Reding
2021-08-18 15:04         ` Dmitry Osipenko
2021-08-18 13:59   ` Thierry Reding
2021-08-18 15:05     ` Dmitry Osipenko
2021-08-18 16:39       ` Thierry Reding
2021-08-18 16:57         ` Dmitry Osipenko
2021-08-18 17:16           ` Dmitry Osipenko
2021-08-19 16:31           ` Thierry Reding
2021-08-19 22:20             ` Dmitry Osipenko
2021-08-20  2:51             ` Dmitry Osipenko [this message]
2021-08-17  1:27 ` [PATCH v8 07/34] clk: tegra: Support runtime PM and power domain Dmitry Osipenko
2021-08-18 14:07   ` Thierry Reding
2021-08-18 15:05     ` Dmitry Osipenko
2021-08-18 16:42       ` Thierry Reding
2021-08-18 17:11         ` Dmitry Osipenko
2021-08-19 16:54           ` Thierry Reding
2021-08-19 22:09             ` Dmitry Osipenko
2021-08-20 11:42               ` Thierry Reding
2021-08-20 13:08                 ` Ulf Hansson
2021-08-21 17:45                   ` Dmitry Osipenko
2021-08-23 14:33                     ` Thierry Reding
2021-08-23 18:54                       ` Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 08/34] dt-bindings: host1x: Document OPP and power domain properties Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 09/34] dt-bindings: host1x: Document Memory Client resets of Host1x, GR2D and GR3D Dmitry Osipenko
2021-08-18  1:16   ` Rob Herring
2021-08-18  1:37     ` Dmitry Osipenko
2021-08-18  2:04       ` Dmitry Osipenko
2021-08-18  2:07         ` Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 10/34] gpu: host1x: Add host1x_channel_stop() Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 11/34] gpu: host1x: Add runtime PM and OPP support Dmitry Osipenko
2021-08-17 12:04   ` Ulf Hansson
2021-08-17 14:02     ` Thierry Reding
2021-08-18  8:35       ` Ulf Hansson
2021-08-18 17:24         ` Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 12/34] drm/tegra: dc: Support OPP and SoC core voltage scaling Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 13/34] drm/tegra: hdmi: Add OPP support Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 14/34] drm/tegra: gr2d: Support power management Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 15/34] drm/tegra: gr3d: " Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 16/34] drm/tegra: vic: Support system suspend Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 17/34] usb: chipidea: tegra: Add runtime PM and OPP support Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 18/34] bus: tegra-gmi: " Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 19/34] pwm: tegra: " Dmitry Osipenko
2021-08-19 13:21   ` Thierry Reding
2021-08-19 14:04     ` Ulf Hansson
2021-08-19 16:17       ` Thierry Reding
2021-08-17  1:27 ` [PATCH v8 20/34] mmc: sdhci-tegra: " Dmitry Osipenko
2021-08-19 17:03   ` Thierry Reding
2021-08-19 22:37     ` Dmitry Osipenko
2021-08-20 11:35       ` Thierry Reding
2021-08-25  9:45         ` Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 21/34] mtd: rawnand: tegra: " Dmitry Osipenko
2021-08-17  8:41   ` Miquel Raynal
2021-08-17  1:27 ` [PATCH v8 22/34] spi: tegra20-slink: Add " Dmitry Osipenko
2021-08-17 12:22   ` Mark Brown
2021-08-17 15:53     ` Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 23/34] media: dt: bindings: tegra-vde: Convert to schema Dmitry Osipenko
2021-08-18  1:17   ` Rob Herring
2021-08-17  1:27 ` [PATCH v8 24/34] media: dt: bindings: tegra-vde: Document OPP and power domain Dmitry Osipenko
2021-08-18  1:17   ` Rob Herring
2021-08-17  1:27 ` [PATCH v8 25/34] media: staging: tegra-vde: Support generic power domain and OPP Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 26/34] soc/tegra: fuse: Add OPP support Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 27/34] soc/tegra: fuse: Reset hardware Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 28/34] soc/tegra: regulators: Prepare for suspend Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 29/34] soc/tegra: pmc: Enable core domain support for Tegra20 and Tegra30 Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 30/34] ARM: tegra: Add OPP tables and power domains to Tegra20 device-trees Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 31/34] ARM: tegra: Add OPP tables and power domains to Tegra30 device-trees Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 32/34] ARM: tegra: Add Memory Client resets to Tegra20 GR2D, GR3D and Host1x Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 33/34] ARM: tegra: Add Memory Client resets to Tegra30 " Dmitry Osipenko
2021-08-17  1:27 ` [PATCH v8 34/34] ARM: tegra20/30: Disable unused host1x hardware Dmitry Osipenko

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