From: Rob Herring <robh@kernel.org> To: Hector Martin <marcan@marcan.st> Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, Marc Zyngier <maz@kernel.org>, Arnd Bergmann <arnd@kernel.org>, Linus Walleij <linus.walleij@linaro.org>, Alyssa Rosenzweig <alyssa@rosenzweig.io>, Krzysztof Kozlowski <krzk@kernel.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mark Kettenis <mark.kettenis@xs4all.nl>, Philipp Zabel <p.zabel@pengutronix.de>, "Rafael J. Wysocki" <rafael@kernel.org>, Johan Hovold <johan@kernel.org>, devicetree@vger.kernel.org, "open list:THERMAL" <linux-pm@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linux-samsung-soc <linux-samsung-soc@vger.kernel.org>, "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>, Mark Kettenis <kettenis@openbsd.org> Subject: Re: [PATCH v2 2/8] dt-bindings: arm: apple: Add apple,pmgr binding Date: Wed, 27 Oct 2021 09:43:54 -0500 [thread overview] Message-ID: <CAL_JsqJbVcqy8n0EroV=nFZoJ_WAr+JbrDf-c1jso856NghC2A@mail.gmail.com> (raw) In-Reply-To: <c0f2587c-ab69-8194-e618-ce7919c1aeb1@marcan.st> On Tue, Oct 26, 2021 at 10:38 PM Hector Martin <marcan@marcan.st> wrote: > > On 27/10/2021 03.25, Rob Herring wrote: > > On Mon, Oct 25, 2021 at 11:47:12PM +0900, Hector Martin wrote: > >> + compatible: > >> + items: > >> + - enum: > >> + - apple,t8103-pmgr > >> + - apple,t8103-minipmgr > >> + - const: apple,pmgr > >> + - const: syscon > >> + - const: simple-mfd > > > > > > 'simple-mfd' means 'there's nothing in this node that any of the child > > nodes depend on'. You should be somewhat certain as dropping it later > > creates compatibility issues. > > Hmm, I see simple-mfd turns this into a bus which I guess allows child > nodes to be probed without the parent node doing anything special (then > we use syscon_node_to_regmap to get the syscon instantiated). Do you > have a example use case for doing this without simple-mfd? Drivers calling of_platform_populate or devm_of_platform_populate. That of course does mean you need a driver. We could probably make the syscon driver call these if needed. > At this point I can't think of anything we'd need from the parent node, > especially if we end up using this syscon strictly for pwrstate subnodes > (which seems likely at this point). One thing that comes to mind is > telling the PMP (a coprocessor in charge of power metrics/management) > about some domains being turned on/off, which is apparently a thing, but > that wouldn't even be in this node; that'd have to be a phandle property > in the child nodes referencing a PMP/coprocessor node elsewhere (none of > which is implemented right now, and which should be backwards compatible > once it is). > > If it turns out we do have a dep of some sort in the end, could we just > have the child node driver return -EPROBE_DEFER until the parent is > probed and has made whatever service available? That would allow us to > keep simple-mfd, right? That would have saved you, but deferred probe is now a fallback to fw_devlink and it makes sure parent driver probes first. That works unless there isn't a parent driver which is often the case for simple-bus[1]. I think you are okay since 'syscon' means there is a driver. > If it works for you, I'll also just squash the two bindings into one > commit for the next spin, since there is a direct dependency at this > point and it should make things easier. Otherwise, I can just swap the > order if you prefer it that way. Just swapping seems like less work, but either way. Rob [1] https://lore.kernel.org/all/CAL_JsqJcsqjJBe8aULYYMkFtx8OTj2wHANZ=83VMMyJ=AEgReg@mail.gmail.com/
WARNING: multiple messages have this Message-ID (diff)
From: Rob Herring <robh@kernel.org> To: Hector Martin <marcan@marcan.st> Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, Marc Zyngier <maz@kernel.org>, Arnd Bergmann <arnd@kernel.org>, Linus Walleij <linus.walleij@linaro.org>, Alyssa Rosenzweig <alyssa@rosenzweig.io>, Krzysztof Kozlowski <krzk@kernel.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Mark Kettenis <mark.kettenis@xs4all.nl>, Philipp Zabel <p.zabel@pengutronix.de>, "Rafael J. Wysocki" <rafael@kernel.org>, Johan Hovold <johan@kernel.org>, devicetree@vger.kernel.org, "open list:THERMAL" <linux-pm@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, linux-samsung-soc <linux-samsung-soc@vger.kernel.org>, "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>, Mark Kettenis <kettenis@openbsd.org> Subject: Re: [PATCH v2 2/8] dt-bindings: arm: apple: Add apple,pmgr binding Date: Wed, 27 Oct 2021 09:43:54 -0500 [thread overview] Message-ID: <CAL_JsqJbVcqy8n0EroV=nFZoJ_WAr+JbrDf-c1jso856NghC2A@mail.gmail.com> (raw) In-Reply-To: <c0f2587c-ab69-8194-e618-ce7919c1aeb1@marcan.st> On Tue, Oct 26, 2021 at 10:38 PM Hector Martin <marcan@marcan.st> wrote: > > On 27/10/2021 03.25, Rob Herring wrote: > > On Mon, Oct 25, 2021 at 11:47:12PM +0900, Hector Martin wrote: > >> + compatible: > >> + items: > >> + - enum: > >> + - apple,t8103-pmgr > >> + - apple,t8103-minipmgr > >> + - const: apple,pmgr > >> + - const: syscon > >> + - const: simple-mfd > > > > > > 'simple-mfd' means 'there's nothing in this node that any of the child > > nodes depend on'. You should be somewhat certain as dropping it later > > creates compatibility issues. > > Hmm, I see simple-mfd turns this into a bus which I guess allows child > nodes to be probed without the parent node doing anything special (then > we use syscon_node_to_regmap to get the syscon instantiated). Do you > have a example use case for doing this without simple-mfd? Drivers calling of_platform_populate or devm_of_platform_populate. That of course does mean you need a driver. We could probably make the syscon driver call these if needed. > At this point I can't think of anything we'd need from the parent node, > especially if we end up using this syscon strictly for pwrstate subnodes > (which seems likely at this point). One thing that comes to mind is > telling the PMP (a coprocessor in charge of power metrics/management) > about some domains being turned on/off, which is apparently a thing, but > that wouldn't even be in this node; that'd have to be a phandle property > in the child nodes referencing a PMP/coprocessor node elsewhere (none of > which is implemented right now, and which should be backwards compatible > once it is). > > If it turns out we do have a dep of some sort in the end, could we just > have the child node driver return -EPROBE_DEFER until the parent is > probed and has made whatever service available? That would allow us to > keep simple-mfd, right? That would have saved you, but deferred probe is now a fallback to fw_devlink and it makes sure parent driver probes first. That works unless there isn't a parent driver which is often the case for simple-bus[1]. I think you are okay since 'syscon' means there is a driver. > If it works for you, I'll also just squash the two bindings into one > commit for the next spin, since there is a direct dependency at this > point and it should make things easier. Otherwise, I can just swap the > order if you prefer it that way. Just swapping seems like less work, but either way. Rob [1] https://lore.kernel.org/all/CAL_JsqJcsqjJBe8aULYYMkFtx8OTj2wHANZ=83VMMyJ=AEgReg@mail.gmail.com/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-10-27 14:44 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-25 14:47 [PATCH v2 0/8] Apple SoC PMGR device power states driver Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 1/8] MAINTAINERS: Add PMGR power state files to ARM/APPLE MACHINE Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 2/8] dt-bindings: arm: apple: Add apple,pmgr binding Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 18:16 ` Rob Herring 2021-10-25 18:16 ` Rob Herring 2021-10-25 18:21 ` Hector Martin 2021-10-25 18:21 ` Hector Martin 2021-10-26 18:25 ` Rob Herring 2021-10-26 18:25 ` Rob Herring 2021-10-27 3:38 ` Hector Martin 2021-10-27 3:38 ` Hector Martin 2021-10-27 14:43 ` Rob Herring [this message] 2021-10-27 14:43 ` Rob Herring 2021-10-27 14:51 ` Krzysztof Kozlowski 2021-10-27 14:51 ` Krzysztof Kozlowski 2021-10-29 7:09 ` Hector Martin 2021-10-29 7:09 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 3/8] dt-bindings: power: Add apple,pmgr-pwrstate binding Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 18:16 ` Rob Herring 2021-10-25 18:16 ` [PATCH v2 3/8] dt-bindings: power: Add apple, pmgr-pwrstate binding Rob Herring 2021-10-26 18:27 ` [PATCH v2 3/8] dt-bindings: power: Add apple,pmgr-pwrstate binding Rob Herring 2021-10-26 18:27 ` Rob Herring 2021-10-25 14:47 ` [PATCH v2 4/8] soc: apple: Add driver for Apple PMGR power state controls Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 5/8] arm64: dts: apple: t8103: Rename clk24 to clkref Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 6/8] arm64: dts: apple: t8103: Add the UART PMGR tree Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 7/8] tty: serial: samsung_tty: Support runtime PM Hector Martin 2021-10-25 14:47 ` Hector Martin 2021-10-25 14:47 ` [PATCH v2 8/8] arm64: dts: apple: t8103: Add UART2 Hector Martin 2021-10-25 14:47 ` Hector Martin
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