Re: [PATCH v3 1/2] dt-bindings: clock: convert rockchip,rk3188-cru.txt to YAML

[Krzysztof Kozlowski]

On 01/04/2022 09:55, Heiko Stübner wrote:
> Hi Stephen,
> 
> Am Freitag, 1. April 2022, 00:51:32 CEST schrieb Stephen Boyd:
>> Quoting Johan Jonker (2022-03-29 04:13:22)
>>> diff --git a/Documentation/devicetree/bindings/clock/rockchip,rk3188-cru.yaml b/Documentation/devicetree/bindings/clock/rockchip,rk3188-cru.yaml
>>> new file mode 100644
>>> index 000000000..ddd7e46af
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/clock/rockchip,rk3188-cru.yaml
>>> @@ -0,0 +1,78 @@
>>> +# SPDX-License-Identifier: GPL-2.0
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/clock/rockchip,rk3188-cru.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: Rockchip RK3188/RK3066 Clock and Reset Unit (CRU)
>>> +
>>> +maintainers:
>>> +  - Elaine Zhang <zhangqing@xxxxxxxxxxxxxx>
>>> +  - Heiko Stuebner <heiko@xxxxxxxxx>
>>> +
>>> +description: |
>>> +  The RK3188/RK3066 clock controller generates and supplies clocks to various
>>> +  controllers within the SoC and also implements a reset controller for SoC
>>> +  peripherals.
>>> +  Each clock is assigned an identifier and client nodes can use this identifier
>>> +  to specify the clock which they consume. All available clocks are defined as
>>> +  preprocessor macros in the dt-bindings/clock/rk3188-cru.h and
>>> +  dt-bindings/clock/rk3066-cru.h headers and can be used in device tree sources.
>>> +  Similar macros exist for the reset sources in these files.
>>> +  There are several clocks that are generated outside the SoC. It is expected
>>> +  that they are defined using standard clock bindings with following
>>> +  clock-output-names:
>>> +    - "xin24m"    - crystal input                 - required
>>> +    - "xin32k"    - RTC clock                     - optional
>>> +    - "xin27m"    - 27mhz crystal input on RK3066 - optional
>>> +    - "ext_hsadc" - external HSADC clock          - optional
>>> +    - "ext_cif0"  - external camera clock         - optional
>>> +    - "ext_rmii"  - external RMII clock           - optional
>>> +    - "ext_jtag"  - external JTAG clock           - optional
>>
>> I'd expect all these clks here to be inputs to this node.
> 
> The optional clocks are all part of a circular dependency.
> 
> So for example xin32k normally is generated by the pmic and fed
> back into the system, so to get xin32k, we need the pmic to probe,
> which needs i2c, which in turn already needs the clock controller.

Are you sure that xin32k (RTC) clock should be input to the clock
controller? I would expect it is the input to the SoC RTC block, so
there is no circular dependency.


Best regards,
Krzysztof