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[88.112.131.206]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-553e41bc2d8sm1407881e87.101.2025.06.23.06.06.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 Jun 2025 06:06:33 -0700 (PDT) Message-ID: <0aaaf251-5070-42b1-99dc-d9f416340335@linaro.org> Date: Mon, 23 Jun 2025 16:06:32 +0300 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 09/10] [RFT] arm64: dts: qcom: sm8250: extend CAMSS with new CSIPHY subdevices To: Neil Armstrong , Krzysztof Kozlowski , Rob Herring , Bjorn Andersson , Konrad Dybcio , Bryan O'Donoghue Cc: Conor Dooley , Robert Foss , Todor Tomov , Mauro Carvalho Chehab , Vinod Koul , linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org References: <20250612011531.2923701-1-vladimir.zapolskiy@linaro.org> <20250612011531.2923701-10-vladimir.zapolskiy@linaro.org> From: Vladimir Zapolskiy In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/23/25 12:31, Neil Armstrong wrote: > On 12/06/2025 03:15, Vladimir Zapolskiy wrote: >> Following the new device tree bindings for CAMSS IPs introduce csiphy2 >> device tree node under SM8250 CAMSS, which allows to perform camera >> tests of the model on an RB5 board with an attached vision mezzanine. >> >> Note that the optional 'phys' property is deliberately not added. >> >> Signed-off-by: Vladimir Zapolskiy >> --- >> For testing only, do not merge. >> >> arch/arm64/boot/dts/qcom/sm8250.dtsi | 14 ++++++++++++++ >> 1 file changed, 14 insertions(+) >> >> diff --git a/arch/arm64/boot/dts/qcom/sm8250.dtsi b/arch/arm64/boot/dts/qcom/sm8250.dtsi >> index f0d18fd37aaf..401a32679580 100644 >> --- a/arch/arm64/boot/dts/qcom/sm8250.dtsi >> +++ b/arch/arm64/boot/dts/qcom/sm8250.dtsi >> @@ -4613,6 +4613,10 @@ camss: camss@ac6a000 { >> "cam_sf_0_mnoc", >> "cam_sf_icp_mnoc"; >> >> + #address-cells = <2>; >> + #size-cells = <2>; >> + ranges; >> + >> ports { >> #address-cells = <1>; >> #size-cells = <0>; >> @@ -4641,6 +4645,16 @@ port@5 { >> reg = <5>; >> }; >> }; >> + >> + csiphy2: phy@ac6e000 { >> + compatible = "qcom,csiphy"; >> + reg = <0 0x0ac6e000 0 0x1000>; >> + clocks = <&camcc CAM_CC_CSIPHY2_CLK>, >> + <&camcc CAM_CC_CSI2PHYTIMER_CLK>; >> + clock-names = "csiphy", "csiphy_timer"; >> + interrupts = ; >> + #phy-cells = <0>; >> + }; > > I would've expected the CSI PHY nodes to be out of the camss node, why would you > keep them as subnodes since you would reference them via phys phandles ? > This is a good question, and it may require a deeper discussion. Below are a few observations and comments supporting the idea of describing CSIPHY IPs as subnodes of CAMSS device tree node. 1. Formally CSIPHY IPs are still parts of CAMSS controller, if the CAMSS IP is considered as a multifunction device containing a number of IP blocks, then it might be logically consistent to place new children device tree nodes under its intermediate parent IP device tree node rather than parent's parent device tree node. 2. Probably a consideration like the one above dictated a placement of Qualcomm DSI PHY (and many other sub-IPs) device tree nodes under a larger MDSS device tree node, here an attempt to repeat the same layout is done. 3. If CSIPHY device tree nodes are completely detached from CAMSS device tree node, then not just "phys" but also new endpoint to endpoint links should be added between CSIPHYs and CSIDs provided by CAMSS like it's dictated by the established scheme of media device connections, however these particular endpoint links are non-fixed and configurable in runtime. The last point can be excluded only if there is a clear agreement that a chain of media endpoint-to-endpoint links from a sensor to ISP is cut between PHY and ISP, with the originally proposed device tree layout scheme it's not a problem, if PHYs are children of the ISP. -- Best wishes, Vladimir