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Message-ID: <752f077d-68a8-4bb5-86cf-c6d49cfe4606@linaro.org>
Date: Thu, 18 Apr 2024 23:56:09 +0300
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Subject: Re: [PATCH V2 RESEND 6/6] arm64: dts: qcom: sm8650: Add video and
 camera clock controllers
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To: Konrad Dybcio <konrad.dybcio@linaro.org>,
 Jagadeesh Kona <quic_jkona@quicinc.com>,
 Bjorn Andersson <andersson@kernel.org>,
 Michael Turquette <mturquette@baylibre.com>, Stephen Boyd
 <sboyd@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 Taniya Das <quic_tdas@quicinc.com>,
 Satya Priya Kakitapalli <quic_skakitap@quicinc.com>,
 Ajit Pandey <quic_ajipan@quicinc.com>,
 Imran Shaik <quic_imrashai@quicinc.com>
References: <20240321092529.13362-1-quic_jkona@quicinc.com>
 <20240321092529.13362-7-quic_jkona@quicinc.com>
 <0a7da687-18fb-437f-b33a-e4a1de20177e@linaro.org>
 <9ac4117c-755e-4e49-b3a2-661e7195a7ed@linaro.org>
From: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
In-Reply-To: <9ac4117c-755e-4e49-b3a2-661e7195a7ed@linaro.org>
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Hi Konrad,

On 3/23/24 02:33, Konrad Dybcio wrote:
> On 21.03.2024 14:07, Vladimir Zapolskiy wrote:
>> Hello Jagadeesh,
>>
>> On 3/21/24 11:25, Jagadeesh Kona wrote:
>>> Add device nodes for video and camera clock controllers on Qualcomm
>>> SM8650 platform.
>>>
>>> Signed-off-by: Jagadeesh Kona <quic_jkona@quicinc.com>
>>> ---
>>>    arch/arm64/boot/dts/qcom/sm8650.dtsi | 28 ++++++++++++++++++++++++++++
>>>    1 file changed, 28 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sm8650.dtsi b/arch/arm64/boot/dts/qcom/sm8650.dtsi
>>> index 32c0a7b9aded..d862aa6be824 100644
>>> --- a/arch/arm64/boot/dts/qcom/sm8650.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sm8650.dtsi
>>> @@ -4,6 +4,8 @@
>>>     */
>>>      #include <dt-bindings/clock/qcom,rpmh.h>
>>> +#include <dt-bindings/clock/qcom,sm8450-videocc.h>
>>> +#include <dt-bindings/clock/qcom,sm8650-camcc.h>
>>>    #include <dt-bindings/clock/qcom,sm8650-dispcc.h>
>>>    #include <dt-bindings/clock/qcom,sm8650-gcc.h>
>>>    #include <dt-bindings/clock/qcom,sm8650-gpucc.h>
>>> @@ -3110,6 +3112,32 @@ opp-202000000 {
>>>                };
>>>            };
>>>    +        videocc: clock-controller@aaf0000 {
>>> +            compatible = "qcom,sm8650-videocc";
>>> +            reg = <0 0x0aaf0000 0 0x10000>;
>>> +            clocks = <&bi_tcxo_div2>,
>>> +                 <&gcc GCC_VIDEO_AHB_CLK>;
>>> +            power-domains = <&rpmhpd RPMHPD_MMCX>;
>>> +            required-opps = <&rpmhpd_opp_low_svs>;
>>
>> Please add default status = "disabled";
>>
>>> +            #clock-cells = <1>;
>>> +            #reset-cells = <1>;
>>> +            #power-domain-cells = <1>;
>>> +        };
>>> +
>>> +        camcc: clock-controller@ade0000 {
>>> +            compatible = "qcom,sm8650-camcc";
>>> +            reg = <0 0x0ade0000 0 0x20000>;
>>> +            clocks = <&gcc GCC_CAMERA_AHB_CLK>,
>>> +                 <&bi_tcxo_div2>,
>>> +                 <&bi_tcxo_ao_div2>,
>>> +                 <&sleep_clk>;
>>> +            power-domains = <&rpmhpd RPMHPD_MMCX>;
>>> +            required-opps = <&rpmhpd_opp_low_svs>;
>>
>> Please add default status = "disabled";
>>
>>> +            #clock-cells = <1>;
>>> +            #reset-cells = <1>;
>>> +            #power-domain-cells = <1>;
>>> +        };
>>> +
>>>            mdss: display-subsystem@ae00000 {
>>>                compatible = "qcom,sm8650-mdss";
>>>                reg = <0 0x0ae00000 0 0x1000>;
>>
>> After disabling the clock controllers
> 
> Clock controllers should never be disabled period, that defeats the
> entire point of having unused clk/pd cleanup.

hm, that's very sane, I didn't think about it from this point, thanks!

> The only reason for them to be disabled is for cases where platform
> crashes on access due to stinky "security" settings (like with audio
> clocks), or when people are too lazy to upstream panel drivers and
> end up partially upstreaming display-related changes and continue
> using the bootloader-initialized framebuffer. This takes away from
> the very little determinism we have.
> 

--
Best wishes,
Vladimir