linux-kernel - Re: [PATCH RFC 1/3] arm64: dts: qcom: sm8750: Add Iris VPU v3.5

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Message-ID: <0debb9a2-2687-4622-ab05-0a3c276f2482@linaro.org>
Date: Wed, 16 Jul 2025 13:30:34 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 1/3] arm64: dts: qcom: sm8750: Add Iris VPU v3.5

On 15/07/2025 12:50, Konrad Dybcio wrote:
>>>>>> +				 <&gcc GCC_VIDEO_AHB_CLK>;
>>>>>> +			power-domains = <&rpmhpd RPMHPD_MMCX>;
>>>>>
>>>>> This is incomplete, need second power domain and I did not check against
>>>>> qcom,sm8750-videocc schema before sending. I will send a v2 a bit later
>>>>> (maybe some reviews pop up).
>>>>
>>>> Heh, no. The DTS here is correct. The videocc bindings are not correct
>>>> (and that's not my patch).
>>>
>>> Well, you want two power domains here in either case..
>> Are you sure? My point was one is correct and downstream confirms that
>> in their bindings (which is a poor argument, I know). Which one would be
>> the second? MM? We don't have such...
> 
> Historically clock controllers used a pair of CX/MX, with CX powering
> the "meat" and MX powering the PLLs (& retention logic, IIUC).
> Over time, CX was split into multiple usecase-specific domains (like
> GFX), and we now have MMCX (or MM_CX - multimedia CX) for multimedia
> hw specifically
> 
> In the downstream tree you're looking at, sun-regulators.dtsi aliases
> VDD_MMCX_LEVEL as VDD_MM_LEVEL for $reasons, which is admittedly a
> little confusing
> 
> MX has similarly been split into MXA (MX-Always [on]) and MXC
> (MX-Collapsible). For Venus, you want the latter, as the hardware is
> not crucial to the functioning of the SoC (the connection is of course


OK, so the binding is correct - the second entry is the MXC power
domain. I'll fix this in v2. Thanks.


Best regards,
Krzysztof