linux-kernel - Re: [PATCH V2 RESEND 6/6] arm64: dts: qcom: sm8650: Add video and camera clock controllers

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Date: Thu, 4 Apr 2024 10:43:25 +0530
From: Jagadeesh Kona <quic_jkona@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        "Krzysztof
 Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Taniya Das
	<quic_tdas@...cinc.com>,
        Satya Priya Kakitapalli <quic_skakitap@...cinc.com>,
        Ajit Pandey <quic_ajipan@...cinc.com>,
        Imran Shaik
	<quic_imrashai@...cinc.com>
Subject: Re: [PATCH V2 RESEND 6/6] arm64: dts: qcom: sm8650: Add video and
 camera clock controllers



On 4/3/2024 9:24 PM, Dmitry Baryshkov wrote:
> On Wed, 3 Apr 2024 at 10:16, Jagadeesh Kona <quic_jkona@...cinc.com> wrote:
>>
>>
>>
>> On 3/25/2024 11:38 AM, Jagadeesh Kona wrote:
>>>
>>>
>>> On 3/21/2024 6:43 PM, Dmitry Baryshkov wrote:
>>>> On Thu, 21 Mar 2024 at 11:27, Jagadeesh Kona <quic_jkona@...cinc.com>
>>>> wrote:
>>>>>
>>>>> Add device nodes for video and camera clock controllers on Qualcomm
>>>>> SM8650 platform.
>>>>>
>>>>> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.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@...0000 {
>>>>> +                       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>;
>>>>
>>>> The required-opps should no longer be necessary.
>>>>
>>>
>>> Sure, will check and remove this if not required.
>>
>>
>> I checked further on this and without required-opps, if there is no vote
>> on the power-domain & its peer from any other consumers, when runtime
>> get is called on device, it enables the power domain just at the minimum
>> non-zero level. But in some cases, the minimum non-zero level of
>> power-domain could be just retention and is not sufficient for clock
>> controller to operate, hence required-opps property is needed to specify
>> the minimum level required on power-domain for this clock controller.
> 
> In which cases? If it ends up with the retention vote, it is a bug
> which must be fixed.
> 

The minimum non-zero level(configured from bootloaders) of MMCX is 
retention on few chipsets but it can vary across the chipsets. Hence to 
be on safer side from our end, it is good to have required-opps in DT to 
specify the minimum level required for this clock controller.

Thanks,
Jagadeesh

>>
>> Thanks,
>> Jagadeesh
>>
>>>
>>>>> +                       #clock-cells = <1>;
>>>>> +                       #reset-cells = <1>;
>>>>> +                       #power-domain-cells = <1>;
>>>>> +               };
>>>>> +
>>>>> +               camcc: clock-controller@...0000 {
>>>>> +                       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>;
>>>>> +                       #clock-cells = <1>;
>>>>> +                       #reset-cells = <1>;
>>>>> +                       #power-domain-cells = <1>;
>>>>> +               };
>>>>> +
>>>>>                   mdss: display-subsystem@...0000 {
>>>>>                           compatible = "qcom,sm8650-mdss";
>>>>>                           reg = <0 0x0ae00000 0 0x1000>;
>>>>> --
>>>>> 2.43.0
>>>>>
>>>>>
>>>>
>>>>
> 
> 
>