linux-kernel - Re: [PATCH 07/13] dt-bindings: media: camss: Add qcom,sm8550-camss binding

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Message-ID: <82dd61ab-83c0-4f9c-a2ee-e00473f4ff23@linaro.org>
Date: Thu, 12 Sep 2024 12:41:23 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
 Depeng Shao <quic_depengs@...cinc.com>, rfoss@...nel.org,
 todor.too@...il.com, mchehab@...nel.org, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org,
 Neil Armstrong <neil.armstrong@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-media@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel@...cinc.com, Yongsheng Li <quic_yon@...cinc.com>
Subject: Re: [PATCH 07/13] dt-bindings: media: camss: Add qcom,sm8550-camss
 binding

On 12/09/2024 09:22, Vladimir Zapolskiy wrote:
>> +
>> +  vdda-phy-supply:
>> +    description:
>> +      Phandle to a regulator supply to PHY core block.
>> +
>> +  vdda-pll-supply:
>> +    description:
>> +      Phandle to 1.2V regulator supply to PHY refclk pll block.
>> +
> 
> Here the supplies should be split into ones, which are specific to CSI 
> blocks,
> and I believe they shall be set as optional.

In principle I agree with that, each CSIPHY should have its own vdda-phy 
and vdda-pll regulator specified.

In practice though I don't believe its necessary, below.

> The proposed names are:
> 
> vdda-phy-01-supply
> vdda-pll-01-supply
> vdda-phy-23-supply
> vdda-pll-23-supply
> vdda-phy-46-supply
> vdda-pll-46-supply
> vdda-phy-57-supply
> vdda-pll-57-supply

In principle, you're right, we need to expand the name set here.

> I understand that what I ask is much more clumsy, and it could be seen 
> even as
> unneeded, however it'll be the right set of properties to describe the 
> CAMSS IP
> in this respect
I think the following naming would be better as it matches the 
power-grid naming in the docs.

csiphyX-vdda-phy-supply
csiphyX-vdda-pll-supply

=>

// voltage domain = vdd_a_csi_01_09 = regulator l1e
csiphy0-vdda-phy-supply = <&vreg_l1e_0p9>;

// voltage domain = vdd_a_csi_01_1p2 = regulator l3e
csiphy0-vdda-pll-supply = <&vreg_l3e_1p2>;

//
csiphy1-vdda-phy-supply = <&vreg_l1e_0p9>;
csiphy1-vdda-pll-supply = <&vreg_l3e_1p2>;

Where X indicates the CSIPHY number.

So in fact, in practice we don't need to differentiate these entries.

Checking x1e80100 ...

csiphy0

vdda-phy-supply = <&vreg_l2c_0p9>;
vdda-pll-supply = <&vreg_l1c_1p2>;

This is also the case for csiphy 1/2/4

So, I _don't_ believe this is work we need to do, since its the same 
regulator for each PHY.

---
bod