linux-kernel - Re: [PATCH] arm64: dts: qcom: qcs615: disable the CTI device of the camera block

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Message-ID: <1fef810c-47fe-4f6d-95bc-0d72dbd63bf0@oss.qualcomm.com>
Date: Tue, 27 May 2025 12:41:14 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Jie Gan <quic_jiegan@...cinc.com>,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Jie Gan <jie.gan@....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: Tingwei Zhang <quic_tingweiz@...cinc.com>,
        Jinlong Mao <quic_jinlmao@...cinc.com>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: qcs615: disable the CTI device of the
 camera block

On 5/27/25 12:32 PM, Jie Gan wrote:
> 
> 
> On 5/27/2025 6:23 PM, Konrad Dybcio wrote:
>> On 5/27/25 3:52 AM, Jie Gan wrote:
>>> Disable the CTI device of the camera block to prevent potential NoC errors
>>> during AMBA bus device matching.
>>>
>>> The clocks for the Qualcomm Debug Subsystem (QDSS) are managed by aoss_qmp
>>> through a mailbox. However, the camera block resides outside the AP domain,
>>> meaning its QDSS clock cannot be controlled via aoss_qmp.
>>
>> Which clock drives it then?
> 
> It's qcom,aoss-qmp.
> 
> clk_prepare->qmp_qdss_clk_prepare
> https://elixir.bootlin.com/linux/v6.15-rc7/source/drivers/soc/qcom/qcom_aoss.c#L280

I'm confused about this part:

> However, the camera block resides outside the AP domain,
> meaning its QDSS clock cannot be controlled via aoss_qmp.

Do we need to poke the QMP of another DRV?

Konrad