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

From: Krzysztof Kozlowski
Date: Sat Apr 02 2022 - 08:16:46 EST


On 02/04/2022 13:45, Johan Jonker wrote:
>
>
> On 4/2/22 13:41, Krzysztof Kozlowski wrote:
>> 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.
>
> clk-rk3188.c:
>
> PNAME(mux_pll_p) = { "xin24m", "xin32k" };

Thanks, but that's not the answer whether it is an input to the clock
controller. It's the answer how the driver implements this. :)

Best regards,
Krzysztof