linux-kernel - Re: [PATCH v6 2/5] dt-bindings: media: Add qcom,x1e80100-camss

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Message-ID: <42b56d7d-26cc-4c10-aca2-a0a5a16b09f6@linaro.org>
Date: Thu, 24 Apr 2025 12:51:31 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
 Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Robert Foss <rfoss@...nel.org>,
 Todor Tomov <todor.too@...il.com>, Mauro Carvalho Chehab
 <mchehab@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>,
 linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org,
 Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
Subject: Re: [PATCH v6 2/5] dt-bindings: media: Add qcom,x1e80100-camss

On 24/04/2025 12:32, Dmitry Baryshkov wrote:
> On Thu, Apr 24, 2025 at 12:29:39PM +0100, Bryan O'Donoghue wrote:
>> On 24/04/2025 11:45, Dmitry Baryshkov wrote:
>>>> Which would then be consistent across SoCs for as long as 0p9 and 1p2 are
>>>> the power-domains used by these PHYs.
>>> This won't be consistent with other cases where we have a shared power
>>> pin. For example, for PMICs we provide supply names which match pin
>>> names rather than one-supply-per-LDO.
>>
>> Yes but taking a random example from a PMIC vdd-l2-l13-l14-supply is
>> specific to a given PMIC, so you need to name it specifically wrt its PMIC
>> pin-name whereas csiphyX-1p2 is there for every CSIPHY we have.
> 
> This is fine from my POV.
> 
>> For example on qcom2290 there's a shared power-pin for VDD_A_CAMSS_PLL_1P8
>> but then individual power-pins for VDD_A_CSI_0_1P2 and VDD_A_CSI_1_1P2.
> 
> So far so good.
> 
>>
>> If we follow the general proposal of
>>
>> vdd-csiphyX-1p2-supply
>> vdd-csiphyX-0p9-supply
>>
>> in the yaml, then whether SoCs like qcm2290 share 1p8 or SoCs like sm8650,
>> sm8450, x1e have individual 1p8 pins is up to the dtsi to decide.
> 
> So, what should be the behaviour if the DT defines different supplies
> for csiphy0 and csiphy1? Would you express that constraint in DT?
> 

You'd have that for qcm2290

yaml:

vdd-csiphy0-1p2-supply
vdd-csiphy1-1p2-supply

vdd-csiphy0-0p8-supply
vdd-csiphy1-0p8-supply

qcm2290-example0.dtsi

vdd-csiphy0-1p2-supply = <&vreg_1p2_ex0>; <- individual supply in PCB
vdd-csiphy1-1p2-supply = <&vreg_1p2_ex1>; <- individual supply in PCB

vdd-csiphy0-0p8-supply = <&vreg_0p9_ex0>; <- shared pin in the SoC
vdd-csiphy1-0p8-supply = <&vreg_0p9_ex0>; <- shared pin in the SoC


qcm2290-example1.dtsi

vdd-csiphy0-1p2-supply = <&vreg_1p2_ex0>; <- shared supply in this PCB
vdd-csiphy1-1p2-supply = <&vreg_1p2_ex0>; <- shared supply in this PCB

vdd-csiphy0-0p8-supply = <&vreg_0p9_ex0>; <- shared pin in the SoC
vdd-csiphy1-0p8-supply = <&vreg_0p9_ex0>; <- shared pin in the SoC

Then sm8650:
yaml:

vdd-csiphy0-1p2-supply
vdd-csiphy1-1p2-supply

vdd-csiphy0-0p8-supply
vdd-csiphy1-0p8-supply


sm8650-example0.dtsi

vdd-csiphy0-1p2-supply = <&vreg_1p2_ex0>; <- individual pin & pcb supply
vdd-csiphy1-1p2-supply = <&vreg_1p2_ex1>; <- individual pin & pcb supply

vdd-csiphy0-0p8-supply = <&vreg_0p9_ex0>; <- individual pin & pcb supply
vdd-csiphy1-0p8-supply = <&vreg_0p9_ex1>; <- individual pin & pcb supply


sm8650-example1.dtsi

vdd-csiphy0-1p2-supply = <&vreg_1p2_ex0>; <- shared supply in this PCB
vdd-csiphy1-1p2-supply = <&vreg_1p2_ex0>; <- shared supply in this PCB

vdd-csiphy0-0p8-supply = <&vreg_0p9_ex0>; <- shared supply in this PCB
vdd-csiphy1-0p8-supply = <&vreg_0p9_ex0>; <- shared supply in this PCB

That way we have a consistent naming across SoCs and PCBs and its up to 
the DT to get the pointer to the regulator right.

---
bod