linux-kernel - Re: [PATCH 3/6] media: qcom: camss: csiphy-3ph: Add Gen2 v1.2.2 two-phase MIPI CSI-2 DPHY init

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Message-ID: <ef218f06-283a-4e7b-bafd-382c47248106@linaro.org>
Date: Sun, 23 Jun 2024 12:17:09 +0100
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: george chan <gchan9527@...il.com>,
 Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, cros-qcom-dts-watchers@...omium.org,
 Bjorn Andersson <andersson@...nel.org>, linux-media@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] media: qcom: camss: csiphy-3ph: Add Gen2 v1.2.2
 two-phase MIPI CSI-2 DPHY init

On 22/06/2024 14:43, george chan wrote:
>     FWIW 1.2.2 seems to be the desired one: [1]
> 
>     Konrad
> 
>     [1]
>     https://git.codelinaro.org/clo/la/kernel/msm-4.14/-/blob/UC.UM.1.0.r1-02500-sa8155.0/arch/arm64/boot/dts/qcom/atoll-camera.dtsi#L22 <https://git.codelinaro.org/clo/la/kernel/msm-4.14/-/blob/UC.UM.1.0.r1-02500-sa8155.0/arch/arm64/boot/dts/qcom/atoll-camera.dtsi#L22>
> 
> 
> Here is the log from sm7125 joyeuse phone, not sure if it helps or not.
> [  204.034767] qcom-camss acb3000.camss: CSIPHY 3PH HW Version = 0x01000000
> 
> I carefully looked into this csiphy_2ph_v1_2_2_reg of various trees, and 
> concluded below version:
> (1)atoll, sdm845[1]
> (2)surya[2], sa8155, factory-trogdor-13443.B-chromeos-5.4[3]
> 
> I was tempted to use (1)atoll one but it looked like (2) is newer. Is it 
> worthy to create CAMSS_7125 specially for SM7125. Please give me some 
> advice about it.

So, which have you tested with as verified and working ?

My assumption here is that this series has been tested and is proven to 
work.

Version 1.2.1 and version 1.2.2 don't indicate different versions of the 
init sequence but different versions of the PHY.

For example - the CSI decoder is "just" digital logic, the "source code" 
for the at logic can be "recompiled" for a different process node.

But the PHYs translate analogue signals into the digital domain and 
therefore will vary with different process nodes - 3nm v 4nm v 28nm.

So it is virtually impossible - or highly improbable that init sequence 
1.2.1 and init sequence 1.2.2 will work on the same piece of hardware.

So its not a question of choosing the newer version - only one version 
will work - the version that is specifically tuned to the PHY for the 
given process node and RTL version.

Err, so TL;DR you _have_ tested this and gotten data delivered to you in 
user-space - right ?

---
bod