linux-kernel - Re: [PATCH 2/3] arm64: dts: qcom: sc7280: Add Camera Control Interface busses

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Date:   Fri, 29 Sep 2023 16:18:56 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Bryan O'Donoghue <pure.logic@...us-software.ie>,
        Luca Weiss <luca.weiss@...rphone.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Andi Shyti <andi.shyti@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        cros-qcom-dts-watchers@...omium.org,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc:     ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] arm64: dts: qcom: sc7280: Add Camera Control
 Interface busses

On 29.09.2023 16:15, Bryan O'Donoghue wrote:
> On 29/09/2023 14:35, Konrad Dybcio wrote:
>>
>>
>> On 9/29/23 10:01, Luca Weiss wrote:
>>> Add the CCI busses found on sc7280 and their pinctrl states.
>>>
>>> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
>>> ---
>>>   arch/arm64/boot/dts/qcom/sc7280.dtsi | 136 +++++++++++++++++++++++++++++++++++
>>>   1 file changed, 136 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>>> index 66f1eb83cca7..65550de2e4ff 100644
>>> --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
>>> @@ -3793,6 +3793,86 @@ videocc: clock-controller@...0000 {
>>>               #power-domain-cells = <1>;
>>>           };
>>> +        cci0: cci@...a000 {
>>> +            compatible = "qcom,sc7280-cci", "qcom,msm8996-cci";
>>> +            reg = <0 0x0ac4a000 0 0x1000>;
>>> +            interrupts = <GIC_SPI 460 IRQ_TYPE_EDGE_RISING>;
>>> +            power-domains = <&camcc CAM_CC_TITAN_TOP_GDSC>;
>>> +
>>> +            clocks = <&camcc CAM_CC_CAMNOC_AXI_CLK>,
>>> +                 <&camcc CAM_CC_SLOW_AHB_CLK_SRC>,
>>> +                 <&camcc CAM_CC_CPAS_AHB_CLK>,
>>> +                 <&camcc CAM_CC_CCI_0_CLK>,
>>> +                 <&camcc CAM_CC_CCI_0_CLK_SRC>;
>>> +            clock-names = "camnoc_axi",
>>> +                      "slow_ahb_src",
>>> +                      "cpas_ahb",
>>> +                      "cci",
>>> +                      "cci_src";
>> I guess this is more of a question to e.g. Bryan, but are all of these clocks actually necessary?
>>
>> Konrad
> Hmm its a good question, we generally take the approach of adopting all of the downstream clocks for these camera interfaces verbatim.
> 
> The clock plan for this part only calls out cci_X_clk and cci_x_clk_src for the CCI however we know that to be incomplete since we *absolutely* need to have the AXI for the block clocked to access those registers, same deal with the AHB bus.
> 
> AXI: registers
> AHB: data
> 
> In the above list the only clock you might conceivably not need is CPAS_AHB_CLK.
> 
> Let me zap that clock from sdm845 since I have an rb3 right in front of me and see what happens.
> 
> Crash and reset
> 
> --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> @@ -4402,13 +4402,11 @@ cci: cci@...a000 {
>                         clocks = <&clock_camcc CAM_CC_CAMNOC_AXI_CLK>,
>                                 <&clock_camcc CAM_CC_SOC_AHB_CLK>,
>                                 <&clock_camcc CAM_CC_SLOW_AHB_CLK_SRC>,
> -                               <&clock_camcc CAM_CC_CPAS_AHB_CLK>,
>                                 <&clock_camcc CAM_CC_CCI_CLK>,
>                                 <&clock_camcc CAM_CC_CCI_CLK_SRC>;
>                         clock-names = "camnoc_axi",
>                                 "soc_ahb",
>                                 "slow_ahb_src",
> -                               "cpas_ahb",
>                                 "cci",
>                                 "cci_src";
> 
> 
> I think the list is good tbh
WDYT about camcc consuming ahb, like dispcc does?
AXI, hmm.. not quite sure what to do with it

Konrad