Re: [PATCH 01/12] dt-bindings: power: Add bindings for the Mediatek SCPSYS power domains controller

Enric Balletbo i Serra
2020-09-23T16:12:37Z

Hi Rob,

Thank you for your answer. I have some doubts, see below.

On 23/9/20 0:36, Rob Herring wrote:
> On Mon, Sep 14, 2020 at 2:59 AM Matthias Brugger <matthias.bgg@gmail.com> wrote:
>>
>>
>>
>> On 12/09/2020 01:02, Rob Herring wrote:
>>> On Thu, Sep 10, 2020 at 07:28:15PM +0200, Enric Balletbo i Serra wrote:
>>>> The System Control Processor System (SCPSYS) has several power management
>>>> related tasks in the system. Add the bindings to define the power
>>>> domains for the SCPSYS power controller.
>>>>
>>>> Co-developed-by: Matthias Brugger <mbrugger@suse.com>
>>>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>>>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>>>> ---
>>>> Dear Rob,
>>>>
>>>> I am awasre that this binding is not ready, but I prefered to send because I'm
>>>> kind of blocked. Compiling this binding triggers the following error:
>>>>
>>>> mediatek,power-controller.example.dt.yaml: syscon@10006000: mfg_async@7:
>>>> '#address-cells', '#size-cells', 'mfg_2d@8'
>>>> do not match any of the regexes: 'pinctrl-[0-9]+'
>>>>
>>>> This happens when a definition of a power-domain (parent) contains
>>>> another power-domain (child), like the example. I am not sure how to
>>>> specify this in the yaml and deal with this, so any clue is welcome.
>>>
>>> You just have to keep nesting schemas all the way down. Define a
>>> grandchild node under the child node and then all of its properties.
>>>
>>>>
>>>> Thanks,
>>>> Enric
>>>>
>>>> .../power/mediatek,power-controller.yaml | 171 ++++++++++++++++++
>>>> 1 file changed, 171 insertions(+)
>>>> create mode 100644 Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml b/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>>>> new file mode 100644
>>>> index 000000000000..8be9244ad160
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>>>> @@ -0,0 +1,171 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/power/mediatek,power-controller.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: Mediatek Power Domains Controller
>>>> +
>>>> +maintainers:
>>>> + - Weiyi Lu <weiyi.lu@mediatek.com>
>>>> + - Matthias Brugger <mbrugger@suse.com>
>>>> +
>>>> +description: |
>>>> + Mediatek processors include support for multiple power domains which can be
>>>> + powered up/down by software based on different application scenes to save power.
>>>> +
>>>> + IP cores belonging to a power domain should contain a 'power-domains'
>>>> + property that is a phandle for SCPSYS node representing the domain.
>>>> +
>>>> +properties:
>>>> + $nodename:
>>>> + pattern: "^syscon@[0-9a-f]+$"
>>>> +
>>>> + compatible:
>>>> + items:
>>>> + - enum:
>>>> + - mediatek,mt8173-power-controller
>>>> + - const: syscon
>>>> +
>>>> + reg:
>>>> + maxItems: 1
>>>> +
>>>> +patternProperties:
>>>> + "^.*@[0-9]$":
>>>
>>> Node names should be generic:
>>>
>>> power-domain@
>>>
>>
>> Enric correct me if I'm wrong, if we want to see the power domains in debugfs,
>> they are listed by their name. If all are called power-domain then the listing
>> is pretty much useless.
>
> Sorry, but not a binding problem.
>
> Maybe if debugfs shows what devices are contained within a power
> domain then it doesn't matter so much.
>
>>>> + type: object
>>>> + description: |
>>>> + Represents the power domains within the power controller node as documented
>>>> + in Documentation/devicetree/bindings/power/power-domain.yaml.
>>>> +
>>>> + properties:
>>>> + reg:
>>>> + description: |
>>>> + Power domain index. Valid values are defined in:
>>>> + "include/dt-bindings/power/mt8173-power.h" - for MT8173 type power domain.
>>>> + maxItems: 1
>>>> +
>>>> + '#power-domain-cells':
>>>> + description:
>>>> + Documented by the generic PM Domain bindings in
>>>> + Documentation/devicetree/bindings/power/power-domain.yaml.
>>>
>>> No need to redefine a common property. This should define valid values
>>> for it.
>>>
>>>> +
>>>> + clocks:
>>>> + description: |
>>>> + A number of phandles to clocks that need to be enabled during domain
>>>> + power-up sequencing.
>>>
>>> No need to redefine 'clocks'. You need to define how many, what each one
>>> is, and the order.
>>>
>>
>> Do you mean we have to define each clock for each power domain of each SoC?
>
> Yes.
>

But every power domain can use totally different clocks I.e in the scpsys
controller for MT8173 we can have:

clocks:
items:
- description: MMSYS reference clock
- description: Video Encoder reference clock

That matches with:

+ power-domain@MT8173_POWER_DOMAIN_VENC {
+ reg = <MT8173_POWER_DOMAIN_VENC>;
+ clocks = <&topckgen CLK_TOP_MM_SEL>,
+ <&topckgen CLK_TOP_VENC_SEL>;
+ clock-names = "mm", "venc";
+ #power-domain-cells = <0>;
+ };

But then we can have another power-domain (inside) with another clock.

+ power-domain@MT8173_POWER_DOMAIN_MFG_ASYNC {
+ reg = <MT8173_POWER_DOMAIN_MFG_ASYNC>;
+ clocks = <&clk26m>;
+ clock-names = "mfg";
+ };

Should we add a new item like this then?

- description: 26MHz reference clock

But clocks will not match with the order for this power-domain (as MMSYS and
VENC clocks are missing here). AFAIK is not possible to specify different clocks
for different power-domains that are inside the SCPSYS power controller node.

For other SoCs we can have something more complex like this:

+ power-domain@MT8183_POWER_DOMAIN_CAM {
+ reg = <MT8183_POWER_DOMAIN_CAM>;
+ clocks = <&topckgen CLK_TOP_MUX_CAM>,
+ <&camsys CLK_CAM_LARB6>,
+ <&camsys CLK_CAM_LARB3>,
+ <&camsys CLK_CAM_SENINF>,
+ <&camsys CLK_CAM_CAMSV0>,
+ <&camsys CLK_CAM_CAMSV1>,
+ <&camsys CLK_CAM_CAMSV2>,
+ <&camsys CLK_CAM_CCU>;
+ clock-names = "cam", "cam-0", "cam-1",
+ "cam-2", "cam-3", "cam-4",
+ "cam-5", "cam-6";
+ mediatek,infracfg = <&infracfg>;
+ mediatek,smi = <&smi_common>;
+ #power-domain-cells = <0>;
+ };

Thanks,
Enric

> Rob
>