| Message ID | 20210817012754.8710-7-digetx@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | NVIDIA Tegra power management patches for 5.16 | expand |
On Tue, Aug 17, 2021 at 04:27:26AM +0300, Dmitry Osipenko wrote: > Document tegra-clocks sub-node which describes Tegra SoC clocks that > require a higher voltage of the core power domain in order to operate > properly on a higher clock rates. Each node contains a phandle to OPP > table and power domain. > > The root PLLs and system clocks don't have any specific device dedicated > to them, clock controller is in charge of managing power for them. > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > .../bindings/clock/nvidia,tegra20-car.yaml | 51 +++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > index 459d2a525393..7f5cd27e4ce0 100644 > --- a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > @@ -42,6 +42,48 @@ properties: > "#reset-cells": > const: 1 > > + tegra-clocks: > + description: child nodes are the output clocks from the CAR > + type: object > + > + patternProperties: > + "^[a-z]+[0-9]+$": > + type: object > + properties: > + compatible: > + allOf: > + - items: > + - enum: > + - nvidia,tegra20-sclk > + - nvidia,tegra30-sclk > + - nvidia,tegra30-pllc > + - nvidia,tegra30-plle > + - nvidia,tegra30-pllm > + - const: nvidia,tegra-clock You are saying the first string must be both one of the enums and 'nvidia,tegra-clock'. You don't get an error because your pattern doesn't match 'sclk'. > + > + operating-points-v2: > + $ref: /schemas/types.yaml#/definitions/phandle > + description: > + Phandle to OPP table that contains frequencies, voltages and > + opp-supported-hw property, which is a bitfield indicating > + SoC process or speedo ID mask. Just 'operating-points-v2: true' is enough. > + > + clocks: > + items: > + - description: node's clock > + > + power-domains: > + maxItems: 1 > + description: phandle to the core SoC power domain > + > + required: > + - compatible > + - operating-points-v2 > + - clocks > + - power-domains > + > + additionalProperties: false > + > required: > - compatible > - reg > @@ -59,6 +101,15 @@ examples: > reg = <0x60006000 0x1000>; > #clock-cells = <1>; > #reset-cells = <1>; > + > + tegra-clocks { > + sclk { > + compatible = "nvidia,tegra20-sclk", "nvidia,tegra-clock"; > + operating-points-v2 = <&opp_table>; > + clocks = <&tegra_car TEGRA20_CLK_SCLK>; > + power-domains = <&domain>; > + }; > + }; > }; > > usb-controller@c5004000 { > -- > 2.32.0 > >
18.08.2021 04:15, Rob Herring пишет: >> + tegra-clocks: >> + description: child nodes are the output clocks from the CAR >> + type: object >> + >> + patternProperties: >> + "^[a-z]+[0-9]+$": >> + type: object >> + properties: >> + compatible: >> + allOf: >> + - items: >> + - enum: >> + - nvidia,tegra20-sclk >> + - nvidia,tegra30-sclk >> + - nvidia,tegra30-pllc >> + - nvidia,tegra30-plle >> + - nvidia,tegra30-pllm >> + - const: nvidia,tegra-clock > You are saying the first string must be both one of the enums and > 'nvidia,tegra-clock'. You don't get an error because your pattern > doesn't match 'sclk'. > Could you please rephrase or clarify? If pattern doesn't match 'sclk', then it must match any other enum. I'm not sure what you're meaning. The 'nvidia,tegra-clock' actually could be removed since it's superfluous now. I'll consider the removal in v9.
On Wed, Aug 18, 2021 at 04:44:30AM +0300, Dmitry Osipenko wrote: > 18.08.2021 04:15, Rob Herring пишет: > >> + tegra-clocks: > >> + description: child nodes are the output clocks from the CAR > >> + type: object > >> + > >> + patternProperties: > >> + "^[a-z]+[0-9]+$": > >> + type: object > >> + properties: > >> + compatible: > >> + allOf: > >> + - items: > >> + - enum: > >> + - nvidia,tegra20-sclk > >> + - nvidia,tegra30-sclk > >> + - nvidia,tegra30-pllc > >> + - nvidia,tegra30-plle > >> + - nvidia,tegra30-pllm > >> + - const: nvidia,tegra-clock > > You are saying the first string must be both one of the enums and > > 'nvidia,tegra-clock'. You don't get an error because your pattern > > doesn't match 'sclk'. > > > > Could you please rephrase or clarify? If pattern doesn't match 'sclk', > then it must match any other enum. I'm not sure what you're meaning. "sclk" doesn't match "^[a-z]+[0-9]+$" because it's missing at least one digit at the end. Perhaps that last + was supposed to be *? > > The 'nvidia,tegra-clock' actually could be removed since it's > superfluous now. I'll consider the removal in v9. It also looks like your schema was meant to be something like: compatible: - items: - enum: - nvidia,tegra20-sclk - nvidia,tegra30-sclk - nvidia,tegra30-pllc - nvidia,tegra30-plle - nvidia,tegra30-pllm - const: nvidia,tegra-clock Note how the const: element is indented one more level. Now this means: one of the enumeration values, followed by the constant value. That matches what the example has. That said, I agree that nvidia,tegra-clock seems a bit useless. There's really no such thing as a generic clock, they're all different in some way. Thierry
On Tue, Aug 17, 2021 at 04:27:26AM +0300, Dmitry Osipenko wrote: > Document tegra-clocks sub-node which describes Tegra SoC clocks that > require a higher voltage of the core power domain in order to operate > properly on a higher clock rates. Each node contains a phandle to OPP > table and power domain. > > The root PLLs and system clocks don't have any specific device dedicated > to them, clock controller is in charge of managing power for them. > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > --- > .../bindings/clock/nvidia,tegra20-car.yaml | 51 +++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > index 459d2a525393..7f5cd27e4ce0 100644 > --- a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > @@ -42,6 +42,48 @@ properties: > "#reset-cells": > const: 1 > > + tegra-clocks: > + description: child nodes are the output clocks from the CAR > + type: object > + > + patternProperties: > + "^[a-z]+[0-9]+$": > + type: object > + properties: > + compatible: > + allOf: > + - items: > + - enum: > + - nvidia,tegra20-sclk > + - nvidia,tegra30-sclk > + - nvidia,tegra30-pllc > + - nvidia,tegra30-plle > + - nvidia,tegra30-pllm > + - const: nvidia,tegra-clock > + > + operating-points-v2: > + $ref: /schemas/types.yaml#/definitions/phandle > + description: > + Phandle to OPP table that contains frequencies, voltages and > + opp-supported-hw property, which is a bitfield indicating > + SoC process or speedo ID mask. > + > + clocks: > + items: > + - description: node's clock > + > + power-domains: > + maxItems: 1 > + description: phandle to the core SoC power domain > + > + required: > + - compatible > + - operating-points-v2 > + - clocks > + - power-domains > + > + additionalProperties: false > + > required: > - compatible > - reg > @@ -59,6 +101,15 @@ examples: > reg = <0x60006000 0x1000>; > #clock-cells = <1>; > #reset-cells = <1>; > + > + tegra-clocks { > + sclk { > + compatible = "nvidia,tegra20-sclk", "nvidia,tegra-clock"; > + operating-points-v2 = <&opp_table>; > + clocks = <&tegra_car TEGRA20_CLK_SCLK>; > + power-domains = <&domain>; > + }; > + }; I wonder if it'd be better to match on the name of the node rather than add an artificial compatible string. We usually use the compatible string to match a device, but here you're really trying to add information about a resource provided by the CAR controller. We do similar things for example in PMIC bindings where the individual regulators are represented in the device tree via nodes named after the regulator. You could then also leave out the clocks property, which is weird as it is because it's basically a self-reference. But you don't really need the reference here in the first place because the CAR is already the parent of SCLK. Also, I don't think the tegra- prefix is necessary here. The parent node is already identified as Tegra via the compatible string. In the case of CAR, I'd imagine something like: clocks { sclk { operating-points-v2 = <&opp_table>; power-domains = <&domain>; }; }; Now you've only got the bare minimum in here that you actually add. All the other data that you used to have is simply derived from the parent. Thierry > }; > > usb-controller@c5004000 { > -- > 2.32.0 >
18.08.2021 16:52, Thierry Reding пишет: > On Wed, Aug 18, 2021 at 04:44:30AM +0300, Dmitry Osipenko wrote: >> 18.08.2021 04:15, Rob Herring пишет: >>>> + tegra-clocks: >>>> + description: child nodes are the output clocks from the CAR >>>> + type: object >>>> + >>>> + patternProperties: >>>> + "^[a-z]+[0-9]+$": >>>> + type: object >>>> + properties: >>>> + compatible: >>>> + allOf: >>>> + - items: >>>> + - enum: >>>> + - nvidia,tegra20-sclk >>>> + - nvidia,tegra30-sclk >>>> + - nvidia,tegra30-pllc >>>> + - nvidia,tegra30-plle >>>> + - nvidia,tegra30-pllm >>>> + - const: nvidia,tegra-clock >>> You are saying the first string must be both one of the enums and >>> 'nvidia,tegra-clock'. You don't get an error because your pattern >>> doesn't match 'sclk'. >>> >> >> Could you please rephrase or clarify? If pattern doesn't match 'sclk', >> then it must match any other enum. I'm not sure what you're meaning. > > "sclk" doesn't match "^[a-z]+[0-9]+$" because it's missing at least one > digit at the end. Perhaps that last + was supposed to be *? Ah, the regex pattern. Yes, I forgot to update it. >> The 'nvidia,tegra-clock' actually could be removed since it's >> superfluous now. I'll consider the removal in v9. > > It also looks like your schema was meant to be something like: > > compatible: > - items: > - enum: > - nvidia,tegra20-sclk > - nvidia,tegra30-sclk > - nvidia,tegra30-pllc > - nvidia,tegra30-plle > - nvidia,tegra30-pllm > - const: nvidia,tegra-clock > > Note how the const: element is indented one more level. Now this means: > one of the enumeration values, followed by the constant value. That > matches what the example has. > > That said, I agree that nvidia,tegra-clock seems a bit useless. There's > really no such thing as a generic clock, they're all different in some > way. It's a leftover from older versions of this patchset, I'll remove it.
18.08.2021 16:59, Thierry Reding пишет: > On Tue, Aug 17, 2021 at 04:27:26AM +0300, Dmitry Osipenko wrote: >> Document tegra-clocks sub-node which describes Tegra SoC clocks that >> require a higher voltage of the core power domain in order to operate >> properly on a higher clock rates. Each node contains a phandle to OPP >> table and power domain. >> >> The root PLLs and system clocks don't have any specific device dedicated >> to them, clock controller is in charge of managing power for them. >> >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com> >> --- >> .../bindings/clock/nvidia,tegra20-car.yaml | 51 +++++++++++++++++++ >> 1 file changed, 51 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml >> index 459d2a525393..7f5cd27e4ce0 100644 >> --- a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml >> +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml >> @@ -42,6 +42,48 @@ properties: >> "#reset-cells": >> const: 1 >> >> + tegra-clocks: >> + description: child nodes are the output clocks from the CAR >> + type: object >> + >> + patternProperties: >> + "^[a-z]+[0-9]+$": >> + type: object >> + properties: >> + compatible: >> + allOf: >> + - items: >> + - enum: >> + - nvidia,tegra20-sclk >> + - nvidia,tegra30-sclk >> + - nvidia,tegra30-pllc >> + - nvidia,tegra30-plle >> + - nvidia,tegra30-pllm >> + - const: nvidia,tegra-clock >> + >> + operating-points-v2: >> + $ref: /schemas/types.yaml#/definitions/phandle >> + description: >> + Phandle to OPP table that contains frequencies, voltages and >> + opp-supported-hw property, which is a bitfield indicating >> + SoC process or speedo ID mask. >> + >> + clocks: >> + items: >> + - description: node's clock >> + >> + power-domains: >> + maxItems: 1 >> + description: phandle to the core SoC power domain >> + >> + required: >> + - compatible >> + - operating-points-v2 >> + - clocks >> + - power-domains >> + >> + additionalProperties: false >> + >> required: >> - compatible >> - reg >> @@ -59,6 +101,15 @@ examples: >> reg = <0x60006000 0x1000>; >> #clock-cells = <1>; >> #reset-cells = <1>; >> + >> + tegra-clocks { >> + sclk { >> + compatible = "nvidia,tegra20-sclk", "nvidia,tegra-clock"; >> + operating-points-v2 = <&opp_table>; >> + clocks = <&tegra_car TEGRA20_CLK_SCLK>; >> + power-domains = <&domain>; >> + }; >> + }; > > I wonder if it'd be better to match on the name of the node rather than > add an artificial compatible string. We usually use the compatible > string to match a device, but here you're really trying to add > information about a resource provided by the CAR controller. > > We do similar things for example in PMIC bindings where the individual > regulators are represented in the device tree via nodes named after the > regulator. > > You could then also leave out the clocks property, which is weird as it > is because it's basically a self-reference. But you don't really need > the reference here in the first place because the CAR is already the > parent of SCLK. We don't have a platform device for CaR. I don't see how it's going to work. We need to create a platform device for each RPM-capable clock because that's how RPM works. The compatible string is required for instantiating OF-devices from a node, otherwise we will have to re-invent the OF core. > Also, I don't think the tegra- prefix is necessary here. The parent node > is already identified as Tegra via the compatible string. > > In the case of CAR, I'd imagine something like: > > clocks { > sclk { > operating-points-v2 = <&opp_table>; > power-domains = <&domain>; > }; > }; > > Now you've only got the bare minimum in here that you actually add. All > the other data that you used to have is simply derived from the parent. 'clocks' is already a generic keyword in DT. It's probably not okay to redefine it.
On Wed, Aug 18, 2021 at 06:05:11PM +0300, Dmitry Osipenko wrote: > 18.08.2021 16:59, Thierry Reding пишет: > > On Tue, Aug 17, 2021 at 04:27:26AM +0300, Dmitry Osipenko wrote: > >> Document tegra-clocks sub-node which describes Tegra SoC clocks that > >> require a higher voltage of the core power domain in order to operate > >> properly on a higher clock rates. Each node contains a phandle to OPP > >> table and power domain. > >> > >> The root PLLs and system clocks don't have any specific device dedicated > >> to them, clock controller is in charge of managing power for them. > >> > >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com> > >> --- > >> .../bindings/clock/nvidia,tegra20-car.yaml | 51 +++++++++++++++++++ > >> 1 file changed, 51 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > >> index 459d2a525393..7f5cd27e4ce0 100644 > >> --- a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > >> +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml > >> @@ -42,6 +42,48 @@ properties: > >> "#reset-cells": > >> const: 1 > >> > >> + tegra-clocks: > >> + description: child nodes are the output clocks from the CAR > >> + type: object > >> + > >> + patternProperties: > >> + "^[a-z]+[0-9]+$": > >> + type: object > >> + properties: > >> + compatible: > >> + allOf: > >> + - items: > >> + - enum: > >> + - nvidia,tegra20-sclk > >> + - nvidia,tegra30-sclk > >> + - nvidia,tegra30-pllc > >> + - nvidia,tegra30-plle > >> + - nvidia,tegra30-pllm > >> + - const: nvidia,tegra-clock > >> + > >> + operating-points-v2: > >> + $ref: /schemas/types.yaml#/definitions/phandle > >> + description: > >> + Phandle to OPP table that contains frequencies, voltages and > >> + opp-supported-hw property, which is a bitfield indicating > >> + SoC process or speedo ID mask. > >> + > >> + clocks: > >> + items: > >> + - description: node's clock > >> + > >> + power-domains: > >> + maxItems: 1 > >> + description: phandle to the core SoC power domain > >> + > >> + required: > >> + - compatible > >> + - operating-points-v2 > >> + - clocks > >> + - power-domains > >> + > >> + additionalProperties: false > >> + > >> required: > >> - compatible > >> - reg > >> @@ -59,6 +101,15 @@ examples: > >> reg = <0x60006000 0x1000>; > >> #clock-cells = <1>; > >> #reset-cells = <1>; > >> + > >> + tegra-clocks { > >> + sclk { > >> + compatible = "nvidia,tegra20-sclk", "nvidia,tegra-clock"; > >> + operating-points-v2 = <&opp_table>; > >> + clocks = <&tegra_car TEGRA20_CLK_SCLK>; > >> + power-domains = <&domain>; > >> + }; > >> + }; > > > > I wonder if it'd be better to match on the name of the node rather than > > add an artificial compatible string. We usually use the compatible > > string to match a device, but here you're really trying to add > > information about a resource provided by the CAR controller. > > > > We do similar things for example in PMIC bindings where the individual > > regulators are represented in the device tree via nodes named after the > > regulator. > > > > You could then also leave out the clocks property, which is weird as it > > is because it's basically a self-reference. But you don't really need > > the reference here in the first place because the CAR is already the > > parent of SCLK. > > We don't have a platform device for CaR. I don't see how it's going to > work. We need to create a platform device for each RPM-capable clock > because that's how RPM works. The compatible string is required for > instantiating OF-devices from a node, otherwise we will have to > re-invent the OF core. I think we do have a platform device for CAR. It's just not bound against by the driver because these clock drivers are "special". But from other parts of the series you're already trying to fix that, at least partially. But it doesn't seem right to create a platform device for each RPM- capable clock. Why do they need to be devices? They aren't, so why pretend? Is it that some API that we want to use here requires the struct device? > > Also, I don't think the tegra- prefix is necessary here. The parent node > > is already identified as Tegra via the compatible string. > > > > In the case of CAR, I'd imagine something like: > > > > clocks { > > sclk { > > operating-points-v2 = <&opp_table>; > > power-domains = <&domain>; > > }; > > }; > > > > Now you've only got the bare minimum in here that you actually add. All > > the other data that you used to have is simply derived from the parent. > > 'clocks' is already a generic keyword in DT. It's probably not okay to > redefine it. "clocks" is not a generic keyword. It's the name of a property and given that we're talking about the clock provider here, it doesn't need a clocks property of its own, so it should be fine to use that for the node. Thierry
18.08.2021 19:39, Thierry Reding пишет: >> We don't have a platform device for CaR. I don't see how it's going to >> work. We need to create a platform device for each RPM-capable clock >> because that's how RPM works. The compatible string is required for >> instantiating OF-devices from a node, otherwise we will have to >> re-invent the OF core. > I think we do have a platform device for CAR. It's just not bound > against by the driver because these clock drivers are "special". But > from other parts of the series you're already trying to fix that, at > least partially. > > But it doesn't seem right to create a platform device for each RPM- > capable clock. Why do they need to be devices? They aren't, so why > pretend? Is it that some API that we want to use here requires the > struct device? 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 >>> Also, I don't think the tegra- prefix is necessary here. The parent node >>> is already identified as Tegra via the compatible string. >>> >>> In the case of CAR, I'd imagine something like: >>> >>> clocks { >>> sclk { >>> operating-points-v2 = <&opp_table>; >>> power-domains = <&domain>; >>> }; >>> }; >>> >>> Now you've only got the bare minimum in here that you actually add. All >>> the other data that you used to have is simply derived from the parent. >> 'clocks' is already a generic keyword in DT. It's probably not okay to >> redefine it. > "clocks" is not a generic keyword. It's the name of a property and given > that we're talking about the clock provider here, it doesn't need a > clocks property of its own, so it should be fine to use that for the > node. I'm curious what Rob thinks about it. Rob, does this sound okay to you?
18.08.2021 19:57, Dmitry Osipenko пишет: >>>> Also, I don't think the tegra- prefix is necessary here. The parent node >>>> is already identified as Tegra via the compatible string. >>>> >>>> In the case of CAR, I'd imagine something like: >>>> >>>> clocks { >>>> sclk { >>>> operating-points-v2 = <&opp_table>; >>>> power-domains = <&domain>; >>>> }; >>>> }; >>>> >>>> Now you've only got the bare minimum in here that you actually add. All >>>> the other data that you used to have is simply derived from the parent. >>> 'clocks' is already a generic keyword in DT. It's probably not okay to >>> redefine it. >> "clocks" is not a generic keyword. It's the name of a property and given >> that we're talking about the clock provider here, it doesn't need a >> clocks property of its own, so it should be fine to use that for the >> node. > I'm curious what Rob thinks about it. Rob, does this sound okay to you? I assume dt-schema won't be happy with a different meaning for the 'clocks'.
On Wed, Aug 18, 2021 at 07:57:04PM +0300, Dmitry Osipenko wrote: > 18.08.2021 19:39, Thierry Reding пишет: > >> We don't have a platform device for CaR. I don't see how it's going to > >> work. We need to create a platform device for each RPM-capable clock > >> because that's how RPM works. The compatible string is required for > >> instantiating OF-devices from a node, otherwise we will have to > >> re-invent the OF core. > > I think we do have a platform device for CAR. It's just not bound > > against by the driver because these clock drivers are "special". But > > from other parts of the series you're already trying to fix that, at > > least partially. > > > > But it doesn't seem right to create a platform device for each RPM- > > capable clock. Why do they need to be devices? They aren't, so why > > pretend? Is it that some API that we want to use here requires the > > struct device? > > 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? > >>> Also, I don't think the tegra- prefix is necessary here. The parent node > >>> is already identified as Tegra via the compatible string. > >>> > >>> In the case of CAR, I'd imagine something like: > >>> > >>> clocks { > >>> sclk { > >>> operating-points-v2 = <&opp_table>; > >>> power-domains = <&domain>; > >>> }; > >>> }; > >>> > >>> Now you've only got the bare minimum in here that you actually add. All > >>> the other data that you used to have is simply derived from the parent. > >> 'clocks' is already a generic keyword in DT. It's probably not okay to > >> redefine it. > > "clocks" is not a generic keyword. It's the name of a property and given > > that we're talking about the clock provider here, it doesn't need a > > clocks property of its own, so it should be fine to use that for the > > node. > > I'm curious what Rob thinks about it. Rob, does this sound okay to you? Another alternative would be to omit that level altogether and just make sclk and siblings direct children of the CAR node. Thierry
19.08.2021 19:31, Thierry Reding пишет: >>>>> Also, I don't think the tegra- prefix is necessary here. The parent node >>>>> is already identified as Tegra via the compatible string. >>>>> >>>>> In the case of CAR, I'd imagine something like: >>>>> >>>>> clocks { >>>>> sclk { >>>>> operating-points-v2 = <&opp_table>; >>>>> power-domains = <&domain>; >>>>> }; >>>>> }; >>>>> >>>>> Now you've only got the bare minimum in here that you actually add. All >>>>> the other data that you used to have is simply derived from the parent. >>>> 'clocks' is already a generic keyword in DT. It's probably not okay to >>>> redefine it. >>> "clocks" is not a generic keyword. It's the name of a property and given >>> that we're talking about the clock provider here, it doesn't need a >>> clocks property of its own, so it should be fine to use that for the >>> node. >> I'm curious what Rob thinks about it. Rob, does this sound okay to you? > Another alternative would be to omit that level altogether and just make > sclk and siblings direct children of the CAR node. That can be done.
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.
diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml index 459d2a525393..7f5cd27e4ce0 100644 --- a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.yaml @@ -42,6 +42,48 @@ properties: "#reset-cells": const: 1 + tegra-clocks: + description: child nodes are the output clocks from the CAR + type: object + + patternProperties: + "^[a-z]+[0-9]+$": + type: object + properties: + compatible: + allOf: + - items: + - enum: + - nvidia,tegra20-sclk + - nvidia,tegra30-sclk + - nvidia,tegra30-pllc + - nvidia,tegra30-plle + - nvidia,tegra30-pllm + - const: nvidia,tegra-clock + + operating-points-v2: + $ref: /schemas/types.yaml#/definitions/phandle + description: + Phandle to OPP table that contains frequencies, voltages and + opp-supported-hw property, which is a bitfield indicating + SoC process or speedo ID mask. + + clocks: + items: + - description: node's clock + + power-domains: + maxItems: 1 + description: phandle to the core SoC power domain + + required: + - compatible + - operating-points-v2 + - clocks + - power-domains + + additionalProperties: false + required: - compatible - reg @@ -59,6 +101,15 @@ examples: reg = <0x60006000 0x1000>; #clock-cells = <1>; #reset-cells = <1>; + + tegra-clocks { + sclk { + compatible = "nvidia,tegra20-sclk", "nvidia,tegra-clock"; + operating-points-v2 = <&opp_table>; + clocks = <&tegra_car TEGRA20_CLK_SCLK>; + power-domains = <&domain>; + }; + }; }; usb-controller@c5004000 {
Document tegra-clocks sub-node which describes Tegra SoC clocks that require a higher voltage of the core power domain in order to operate properly on a higher clock rates. Each node contains a phandle to OPP table and power domain. The root PLLs and system clocks don't have any specific device dedicated to them, clock controller is in charge of managing power for them. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> --- .../bindings/clock/nvidia,tegra20-car.yaml | 51 +++++++++++++++++++ 1 file changed, 51 insertions(+)