mbox series

[v8,00/34] NVIDIA Tegra power management patches for 5.16

Message ID 20210817012754.8710-1-digetx@gmail.com
Headers show
Series NVIDIA Tegra power management patches for 5.16 | expand

Message

Dmitry Osipenko Aug. 17, 2021, 1:27 a.m. UTC
This series adds runtime PM support to Tegra drivers and enables core
voltage scaling for Tegra20/30 SoCs, resolving overheating troubles.

All patches should go via Tegra tree because they are interdependent,
please review and ack.

If you haven't seen this series before, that's because I wanted to
finalize the GENPD part at first and didn't bother you previously.

Changelog:

v8: - Added new generic dev_pm_opp_sync() helper that syncs OPP state with
      hardware. All drivers changed to use it. This replaces GENPD attach_dev
      callback hacks that were used in v7.

    - Added new patch patch "soc/tegra: regulators: Prepare for suspend"
      that fixes dying Tegra20 SoC after enabling VENC power domain during
      resume from suspend. It matches to what downstream kernel does on
      suspend/resume.

    - After a second thought, I dropped patches which added RPM to memory
      drivers since hardware is always-on and RPM not needed.

    - Replaced the "dummy host1x driver" patch with new "Disable unused
      host1x hardware" patch, since it's a cleaner solution.

Dmitry Osipenko (34):
  opp: Add dev_pm_opp_sync() helper
  soc/tegra: pmc: Disable PMC state syncing
  soc/tegra: Don't print error message when OPPs not available
  soc/tegra: Add devm_tegra_core_dev_init_opp_table_simple()
  soc/tegra: Use dev_pm_opp_sync()
  dt-bindings: clock: tegra-car: Document new tegra-clocks sub-node
  clk: tegra: Support runtime PM and power domain
  dt-bindings: host1x: Document OPP and power domain properties
  dt-bindings: host1x: Document Memory Client resets of Host1x, GR2D and
    GR3D
  gpu: host1x: Add host1x_channel_stop()
  gpu: host1x: Add runtime PM and OPP support
  drm/tegra: dc: Support OPP and SoC core voltage scaling
  drm/tegra: hdmi: Add OPP support
  drm/tegra: gr2d: Support power management
  drm/tegra: gr3d: Support power management
  drm/tegra: vic: Support system suspend
  usb: chipidea: tegra: Add runtime PM and OPP support
  bus: tegra-gmi: Add runtime PM and OPP support
  pwm: tegra: Add runtime PM and OPP support
  mmc: sdhci-tegra: Add runtime PM and OPP support
  mtd: rawnand: tegra: Add runtime PM and OPP support
  spi: tegra20-slink: Add OPP support
  media: dt: bindings: tegra-vde: Convert to schema
  media: dt: bindings: tegra-vde: Document OPP and power domain
  media: staging: tegra-vde: Support generic power domain and OPP
  soc/tegra: fuse: Add OPP support
  soc/tegra: fuse: Reset hardware
  soc/tegra: regulators: Prepare for suspend
  soc/tegra: pmc: Enable core domain support for Tegra20 and Tegra30
  ARM: tegra: Add OPP tables and power domains to Tegra20 device-trees
  ARM: tegra: Add OPP tables and power domains to Tegra30 device-trees
  ARM: tegra: Add Memory Client resets to Tegra20 GR2D, GR3D and Host1x
  ARM: tegra: Add Memory Client resets to Tegra30 GR2D, GR3D and Host1x
  ARM: tegra20/30: Disable unused host1x hardware

 .../bindings/clock/nvidia,tegra20-car.yaml    |   51 +
 .../display/tegra/nvidia,tegra20-host1x.txt   |   53 +
 .../bindings/media/nvidia,tegra-vde.txt       |   64 -
 .../bindings/media/nvidia,tegra-vde.yaml      |  119 ++
 .../boot/dts/tegra20-acer-a500-picasso.dts    |    1 +
 arch/arm/boot/dts/tegra20-colibri.dtsi        |    3 +-
 arch/arm/boot/dts/tegra20-harmony.dts         |    3 +-
 arch/arm/boot/dts/tegra20-paz00.dts           |    1 +
 .../arm/boot/dts/tegra20-peripherals-opp.dtsi |  941 +++++++++++
 arch/arm/boot/dts/tegra20-seaboard.dts        |    3 +-
 arch/arm/boot/dts/tegra20-tamonten.dtsi       |    3 +-
 arch/arm/boot/dts/tegra20-trimslice.dts       |    9 +
 arch/arm/boot/dts/tegra20-ventana.dts         |    1 +
 arch/arm/boot/dts/tegra20.dtsi                |  119 +-
 .../tegra30-asus-nexus7-grouper-common.dtsi   |    1 +
 arch/arm/boot/dts/tegra30-beaver.dts          |    1 +
 arch/arm/boot/dts/tegra30-cardhu.dtsi         |    1 +
 arch/arm/boot/dts/tegra30-colibri.dtsi        |   17 +-
 arch/arm/boot/dts/tegra30-ouya.dts            |    1 +
 .../arm/boot/dts/tegra30-peripherals-opp.dtsi | 1412 +++++++++++++++++
 arch/arm/boot/dts/tegra30.dtsi                |  181 ++-
 drivers/bus/tegra-gmi.c                       |   92 +-
 drivers/clk/tegra/Makefile                    |    1 +
 drivers/clk/tegra/clk-device.c                |  222 +++
 drivers/clk/tegra/clk-pll.c                   |    2 +-
 drivers/clk/tegra/clk-super.c                 |    2 +-
 drivers/clk/tegra/clk-tegra20.c               |   39 +-
 drivers/clk/tegra/clk-tegra30.c               |   70 +-
 drivers/clk/tegra/clk.c                       |   64 +
 drivers/clk/tegra/clk.h                       |    2 +
 drivers/gpu/drm/tegra/dc.c                    |   74 +
 drivers/gpu/drm/tegra/dc.h                    |    2 +
 drivers/gpu/drm/tegra/gr2d.c                  |  154 +-
 drivers/gpu/drm/tegra/gr3d.c                  |  393 ++++-
 drivers/gpu/drm/tegra/hdmi.c                  |   15 +-
 drivers/gpu/drm/tegra/vic.c                   |    4 +
 drivers/gpu/host1x/channel.c                  |    8 +
 drivers/gpu/host1x/debug.c                    |   15 +
 drivers/gpu/host1x/dev.c                      |  157 +-
 drivers/gpu/host1x/dev.h                      |    3 +-
 drivers/gpu/host1x/hw/channel_hw.c            |   44 +-
 drivers/gpu/host1x/intr.c                     |    3 -
 drivers/gpu/host1x/syncpt.c                   |    5 +-
 drivers/mmc/host/sdhci-tegra.c                |  146 +-
 drivers/mtd/nand/raw/tegra_nand.c             |   62 +-
 drivers/opp/core.c                            |   42 +-
 drivers/pwm/pwm-tegra.c                       |  104 +-
 drivers/soc/tegra/common.c                    |   34 +-
 drivers/soc/tegra/fuse/fuse-tegra.c           |   36 +
 drivers/soc/tegra/fuse/fuse.h                 |    1 +
 drivers/soc/tegra/pmc.c                       |   17 +
 drivers/soc/tegra/regulators-tegra20.c        |   99 ++
 drivers/soc/tegra/regulators-tegra30.c        |  122 ++
 drivers/spi/spi-tegra20-slink.c               |   15 +-
 drivers/staging/media/tegra-vde/vde.c         |   65 +-
 drivers/usb/chipidea/ci_hdrc_tegra.c          |   61 +-
 include/linux/host1x.h                        |    1 +
 include/linux/pm_opp.h                        |    6 +
 include/soc/tegra/common.h                    |   13 +
 59 files changed, 4796 insertions(+), 384 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/media/nvidia,tegra-vde.txt
 create mode 100644 Documentation/devicetree/bindings/media/nvidia,tegra-vde.yaml
 create mode 100644 drivers/clk/tegra/clk-device.c

Comments

Miquel Raynal Aug. 17, 2021, 8:41 a.m. UTC | #1
Hi Dmitry,

Dmitry Osipenko <digetx@gmail.com> wrote on Tue, 17 Aug 2021 04:27:41
+0300:

> The NAND on Tegra belongs to the core power domain and we're going to
> enable GENPD support for the core domain. Now NAND must be resumed using
> runtime PM API in order to initialize the NAND power state. Add runtime PM
> and OPP support to the NAND driver.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/mtd/nand/raw/tegra_nand.c | 62 +++++++++++++++++++++++++++----
>  1 file changed, 54 insertions(+), 8 deletions(-)
> 

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks,
Miquèl
Rob Herring Aug. 18, 2021, 1:17 a.m. UTC | #2
On Tue, 17 Aug 2021 04:27:44 +0300, Dmitry Osipenko wrote:
> Document new OPP table and power domain properties of the video decoder
> hardware.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  .../devicetree/bindings/media/nvidia,tegra-vde.yaml  | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>
Dmitry Osipenko Aug. 18, 2021, 1:44 a.m. UTC | #3
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.
Thierry Reding Aug. 18, 2021, 1:52 p.m. UTC | #4
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
Dmitry Osipenko Aug. 18, 2021, 3:05 p.m. UTC | #5
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.
Dmitry Osipenko Aug. 18, 2021, 4:57 p.m. UTC | #6
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?
Dmitry Osipenko Aug. 18, 2021, 5:16 p.m. UTC | #7
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'.
Thierry Reding Aug. 19, 2021, 1:21 p.m. UTC | #8
On Tue, Aug 17, 2021 at 04:27:39AM +0300, Dmitry Osipenko wrote:
> The PWM on Tegra belongs to the core power domain and we're going to
> enable GENPD support for the core domain. Now PWM must be resumed using
> runtime PM API in order to initialize the PWM power state. The PWM clock
> rate must be changed using OPP API that will reconfigure the power domain
> performance state in accordance to the rate. Add runtime PM and OPP
> support to the PWM driver.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/pwm/pwm-tegra.c | 104 ++++++++++++++++++++++++++++++++--------
>  1 file changed, 85 insertions(+), 19 deletions(-)

Can this be safely applied independently of the rest of the series, or
are there any dependencies on earlier patches?

Thierry
Ulf Hansson Aug. 19, 2021, 2:04 p.m. UTC | #9
On Thu, 19 Aug 2021 at 15:21, Thierry Reding <thierry.reding@gmail.com> wrote:
>

> On Tue, Aug 17, 2021 at 04:27:39AM +0300, Dmitry Osipenko wrote:

> > The PWM on Tegra belongs to the core power domain and we're going to

> > enable GENPD support for the core domain. Now PWM must be resumed using

> > runtime PM API in order to initialize the PWM power state. The PWM clock

> > rate must be changed using OPP API that will reconfigure the power domain

> > performance state in accordance to the rate. Add runtime PM and OPP

> > support to the PWM driver.

> >

> > Signed-off-by: Dmitry Osipenko <digetx@gmail.com>

> > ---

> >  drivers/pwm/pwm-tegra.c | 104 ++++++++++++++++++++++++++++++++--------

> >  1 file changed, 85 insertions(+), 19 deletions(-)

>

> Can this be safely applied independently of the rest of the series, or

> are there any dependencies on earlier patches?


Just to make sure we don't rush something in, I would rather withhold
all runtime PM related patches in the series, until we have agreed on
how to fix the in genpd/opp core parts. Simply, because those may very
well affect the deployments in the drivers.

>

> Thierry


Kind regards
Uffe
Thierry Reding Aug. 19, 2021, 4:17 p.m. UTC | #10
On Thu, Aug 19, 2021 at 04:04:50PM +0200, Ulf Hansson wrote:
> On Thu, 19 Aug 2021 at 15:21, Thierry Reding <thierry.reding@gmail.com> wrote:
> >
> > On Tue, Aug 17, 2021 at 04:27:39AM +0300, Dmitry Osipenko wrote:
> > > The PWM on Tegra belongs to the core power domain and we're going to
> > > enable GENPD support for the core domain. Now PWM must be resumed using
> > > runtime PM API in order to initialize the PWM power state. The PWM clock
> > > rate must be changed using OPP API that will reconfigure the power domain
> > > performance state in accordance to the rate. Add runtime PM and OPP
> > > support to the PWM driver.
> > >
> > > Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> > > ---
> > >  drivers/pwm/pwm-tegra.c | 104 ++++++++++++++++++++++++++++++++--------
> > >  1 file changed, 85 insertions(+), 19 deletions(-)
> >
> > Can this be safely applied independently of the rest of the series, or
> > are there any dependencies on earlier patches?
> 
> Just to make sure we don't rush something in, I would rather withhold
> all runtime PM related patches in the series, until we have agreed on
> how to fix the in genpd/opp core parts. Simply, because those may very
> well affect the deployments in the drivers.

Okay, understood. I didn't realize this may have an impact on how
drivers need to cooperate. I'll hold off on applying any of these
patches until the discussion has settled, then.

Thierry
Dmitry Osipenko Aug. 19, 2021, 10:20 p.m. UTC | #11
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.
Dmitry Osipenko Aug. 20, 2021, 2:51 a.m. UTC | #12
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.
Thierry Reding Aug. 20, 2021, 11:35 a.m. UTC | #13
On Fri, Aug 20, 2021 at 01:37:13AM +0300, Dmitry Osipenko wrote:
> 19.08.2021 20:03, Thierry Reding пишет:
> > On Tue, Aug 17, 2021 at 04:27:40AM +0300, Dmitry Osipenko wrote:
> >> The SDHCI on Tegra belongs to the core power domain and we're going to
> >> enable GENPD support for the core domain. Now SDHCI must be resumed using
> >> runtime PM API in order to initialize the SDHCI power state. The SDHCI
> >> clock rate must be changed using OPP API that will reconfigure the power
> >> domain performance state in accordance to the rate. Add runtime PM and OPP
> >> support to the SDHCI driver.
> >>
> >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> >> ---
> >>  drivers/mmc/host/sdhci-tegra.c | 146 ++++++++++++++++++++++++---------
> >>  1 file changed, 105 insertions(+), 41 deletions(-)
> >>
> >> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> >> index 387ce9cdbd7c..a3583359c972 100644
> >> --- a/drivers/mmc/host/sdhci-tegra.c
> >> +++ b/drivers/mmc/host/sdhci-tegra.c
> >> @@ -15,6 +15,8 @@
> >>  #include <linux/of.h>
> >>  #include <linux/of_device.h>
> >>  #include <linux/pinctrl/consumer.h>
> >> +#include <linux/pm_opp.h>
> >> +#include <linux/pm_runtime.h>
> >>  #include <linux/regulator/consumer.h>
> >>  #include <linux/reset.h>
> >>  #include <linux/mmc/card.h>
> >> @@ -24,6 +26,8 @@
> >>  #include <linux/gpio/consumer.h>
> >>  #include <linux/ktime.h>
> >>  
> >> +#include <soc/tegra/common.h>
> >> +
> >>  #include "sdhci-pltfm.h"
> >>  #include "cqhci.h"
> >>  
> >> @@ -123,6 +127,12 @@
> >>  					 SDHCI_TRNS_BLK_CNT_EN | \
> >>  					 SDHCI_TRNS_DMA)
> >>  
> >> +enum {
> >> +	TEGRA_CLK_BULK_SDHCI,
> >> +	TEGRA_CLK_BULK_TMCLK,
> >> +	TEGRA_CLK_BULK_NUM,
> >> +};
> >> +
> >>  struct sdhci_tegra_soc_data {
> >>  	const struct sdhci_pltfm_data *pdata;
> >>  	u64 dma_mask;
> >> @@ -171,6 +181,8 @@ struct sdhci_tegra {
> >>  	bool enable_hwcq;
> >>  	unsigned long curr_clk_rate;
> >>  	u8 tuned_tap_delay;
> >> +
> >> +	struct clk_bulk_data clocks[TEGRA_CLK_BULK_NUM];
> > 
> > This doesn't seem worth it to me. There's a lot of churn in this driver
> > that's only needed to convert this to the clk_bulk API and it makes the
> > code a lot more difficult to read, in my opinion.
> > 
> > It looks like the only benefit that this gives us is that runtime
> > suspend and resume become a few lines shorter.
> 
> The driver probe code looks cleaner with that. You should be looking at
> the final result and not at the patch to see it.

I did look at the final result and didn't find it cleaner at all. =)

Thierry