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

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Message-ID: <0eed395b-ca02-2308-a5c6-7c4a72720175@gmail.com>
Date:   Sat, 2 Apr 2022 14:20:02 +0200
From:   Johan Jonker <jbx6244@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Heiko Stübner <heiko@...ech.de>,
        zhangqing@...k-chips.com, Stephen Boyd <sboyd@...nel.org>
Cc:     robh+dt@...nel.org, krzk+dt@...nel.org, mturquette@...libre.com,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: clock: convert
 rockchip,rk3188-cru.txt to YAML



On 4/2/22 14:16, Krzysztof Kozlowski wrote:
> 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@...k-chips.com>
>>>>>> +  - Heiko Stuebner <heiko@...ech.de>
>>>>>> +
>>>>>> +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. :)

PX2 == rk3066

Rockchip PX2 TRM V1.0.pdf

page 30

Chip Clock Architecture Diagram 1

> 
> Best regards,
> Krzysztof