From: Viorel Suman <viorel.suman@oss.nxp.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Viorel Suman <viorel.suman@nxp.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
Dong Aisheng <aisheng.dong@nxp.com>,
Fabio Estevam <festevam@gmail.com>,
Shawn Guo <shawnguo@kernel.org>, Stefan Agner <stefan@agner.ch>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Linus Walleij <linus.walleij@linaro.org>,
Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Amit Kucheria <amitk@kernel.org>, Zhang Rui <rui.zhang@intel.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Guenter Roeck <linux@roeck-us.net>,
Sascha Hauer <s.hauer@pengutronix.de>,
NXP Linux Team <linux-imx@nxp.com>,
Abel Vesa <abelvesa@kernel.org>,
Oliver Graute <oliver.graute@kococonnector.com>,
Liu Ying <victor.liu@nxp.com>,
Mirela Rabulea <mirela.rabulea@nxp.com>,
Peng Fan <peng.fan@nxp.com>, Ming Qian <ming.qian@nxp.com>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-clk@vger.kernel.org, linux-input@vger.kernel.org,
linux-gpio@vger.kernel.org, linux-rtc@vger.kernel.org,
linux-pm@vger.kernel.org, linux-watchdog@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 10/14] arm64: dts: freescale: imx8qxp: Remove unnecessary clock related entries
Date: Thu, 30 Jun 2022 22:48:04 +0300 [thread overview]
Message-ID: <20220630194804.sa3mvokpv7iksgbx@fsr-ub1664-116> (raw)
In-Reply-To: <5d8b2044-5ca6-c90c-57b4-afbb2ae20dde@linaro.org>
On 22-06-30 20:01:31, Krzysztof Kozlowski wrote:
> On 30/06/2022 10:36, Viorel Suman wrote:
> > On 22-06-29 20:04:43, Krzysztof Kozlowski wrote:
> >> On 29/06/2022 18:44, Viorel Suman (OSS) wrote:
> >>> From: Viorel Suman <viorel.suman@nxp.com>
> >>>
> >>> "clocks" and "clock-names" are not used the driver, so
> >>> remove them in order to match the yaml definition.
> >>
> >> So this explains the unexpected change in the bindings... but actually
> >> it does not explain whether it is correct or not. Just because driver
> >> does not use it, is not a proof that clocks are not there. In different
> >> OS/implementation this DTS might break stuff, so basically it is ABI
> >> break. DTS should describe the hardware fully, so if the clocks are
> >> there, should be in DTS regardless of the driver.
> >
> > Hi Krzysztof,
> >
> > Both XTAL clocks - 24MHz and 32kHz - are still defined in DTSI files, see for instance in
> > arch/arm64/boot/dts/freescale/imx8qxp.dtsi :
> > ---------------
> > xtal32k: clock-xtal32k {
> > compatible = "fixed-clock";
> > #clock-cells = <0>;
> > clock-frequency = <32768>;
> > clock-output-names = "xtal_32KHz";
> > };
> >
> > xtal24m: clock-xtal24m {
> > compatible = "fixed-clock";
> > #clock-cells = <0>;
> > clock-frequency = <24000000>;
> > clock-output-names = "xtal_24MHz";
> > };
> > ---------------
> > Both can be seen in /sys/kernel/debug/clk/clk_summary once boot is complete, both can be referenced
> > in any DTS node, so there is no ABI break.
>
> ABI break is not relevant to the fixed clocks being or not being defined
> in the DTS. You have a device which was taking the clock inputs, so the
> clocks stayed enabled.
>
> Now, you don't take these inputs, so for example the clocks are getting
> disabled as not used.
Ok, thanks for the explanation.
> >
> > "DTS should describe the hardware fully" - this is true in case the OS is supposed to controll the
> > hardware fully. i.MX8 System Controller Unit concept implies resources being allocated and managed
> > by SCU, there is no direct OS access to some hardware. SCU actually defines the hardware environment
> > the OS is being able to see and run within. SCU is able to define several such isolated hardware
> > environments, each having its own OS running. So, in this particular case - i.MX8 SCU concept -
> > DTS should describe the hardware from the perspective of the hardware environment exposed by SCU to
> > OS.
>
> OK, that sounds good, but the question about these clocks remain - are
> they inputs to the SCU or not.
The question context looks a bit shifted. The "clocks" and "clock-names"
attributes are removed from a clock provider device.
The OS clock provider in this case is a client which uses some protocol
to communicate with SCU via a messaging unit. There is no
access to xtal clocks via the existing OS<->SCU communication protocol.
>
> Regardless whether they are actual input or not, you used not
> appropriate argument here - that Linux OS implementation does not use
> them. The proper argument is - whether the hardware environment has them
> connected or not.
Right, agreed.
Regards,
Viorel
next prev parent reply other threads:[~2022-06-30 19:48 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-29 16:44 [PATCH v6 00/14] dt-bindings: arm: freescale: Switch fsl,scu from txt to yaml Viorel Suman (OSS)
2022-06-29 16:44 ` [PATCH v6 01/14] dt-bindings: clk: imx: Add fsl,scu-clk yaml file Viorel Suman (OSS)
2022-06-29 17:48 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 02/14] dt-bindings: pinctrl: imx: Add fsl,scu-iomux " Viorel Suman (OSS)
2022-06-29 17:53 ` Krzysztof Kozlowski
2022-06-30 12:37 ` Viorel Suman (OSS)
2022-06-30 18:33 ` Krzysztof Kozlowski
2022-07-05 18:33 ` Rob Herring
2022-07-06 14:11 ` Rob Herring
2022-07-06 14:29 ` Krzysztof Kozlowski
2022-06-30 13:44 ` Rob Herring
2022-06-29 16:44 ` [PATCH v6 03/14] dt-bindings: input: Add fsl,scu-key " Viorel Suman (OSS)
2022-06-29 17:54 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 04/14] dt-bindings: nvmem: Add fsl,scu-ocotp " Viorel Suman (OSS)
2022-06-29 17:56 ` Krzysztof Kozlowski
2022-06-29 17:56 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 05/14] dt-bindings: power: Add fsl,scu-pd " Viorel Suman (OSS)
2022-06-29 17:57 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 06/14] dt-bindings: rtc: Add fsl,scu-rtc " Viorel Suman (OSS)
2022-06-29 17:58 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 07/14] dt-bindings: thermal: Add fsl,scu-thermal " Viorel Suman (OSS)
2022-06-29 17:59 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 08/14] dt-bindings: watchdog: Add fsl,scu-wdt " Viorel Suman (OSS)
2022-06-29 17:59 ` Krzysztof Kozlowski
2022-06-30 14:43 ` Guenter Roeck
2022-06-29 16:44 ` [PATCH v6 09/14] dt-bindings: firmware: Add fsl,scu " Viorel Suman (OSS)
2022-06-29 18:02 ` Krzysztof Kozlowski
2022-06-30 13:44 ` Rob Herring
2022-06-29 16:44 ` [PATCH v6 10/14] arm64: dts: freescale: imx8qxp: Remove unnecessary clock related entries Viorel Suman (OSS)
2022-06-29 18:04 ` Krzysztof Kozlowski
2022-06-30 8:36 ` Viorel Suman
2022-06-30 18:01 ` Krzysztof Kozlowski
2022-06-30 19:48 ` Viorel Suman [this message]
2022-07-04 8:06 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 11/14] arm64: dts: freescale: imx8: Fix power controller name Viorel Suman (OSS)
2022-06-29 18:05 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 12/14] arm64: dts: freescale: imx8qxp: Add fallback compatible for clock controller Viorel Suman (OSS)
2022-06-29 18:05 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 13/14] arm64: dts: freescale: imx8qxp: Fix the keys node name Viorel Suman (OSS)
2022-06-29 18:06 ` Krzysztof Kozlowski
2022-06-29 16:44 ` [PATCH v6 14/14] dt-bindings: arm: freescale: Remove fsl,scu txt file Viorel Suman (OSS)
2022-06-29 18:03 ` Krzysztof Kozlowski
2022-06-29 17:51 ` [PATCH v6 00/14] dt-bindings: arm: freescale: Switch fsl,scu from txt to yaml Krzysztof Kozlowski
2022-06-30 12:13 ` Viorel Suman (OSS)
2022-06-30 18:03 ` Krzysztof Kozlowski
2022-06-30 18:11 ` Viorel Suman
2022-07-05 0:39 ` Shawn Guo
2022-07-05 7:28 ` Krzysztof Kozlowski
2022-07-05 8:07 ` Viorel Suman
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