linux-kernel - Re: [PATCH RFC 0/8] media: camss: Add support for C-PHY configuration on Qualcomm platforms

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Message-ID: <0390ae7b-8f56-4ed3-a3f9-616e7c74adbd@linaro.org>
Date: Sun, 9 Nov 2025 13:49:56 +0100
From: Casey Connolly <casey.connolly@...aro.org>
To: david@...t.cz, Robert Foss <rfoss@...nel.org>,
 Todor Tomov <todor.too@...il.com>,
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Luca Weiss <luca.weiss@...rphone.com>, Petr Hodina <phodina@...tonmail.com>,
 "Dr. Git" <drgitx@...il.com>
Cc: Joel Selvaraj <foss@...lselvaraj.com>, linux-media@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
 phone-devel@...r.kernel.org, Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH RFC 0/8] media: camss: Add support for C-PHY configuration
 on Qualcomm platforms

Hi David,

On 11/9/25 10:39, David Heidelberg via B4 Relay wrote:
> # Short summary
> 
> This patch series extends the Qualcomm CAMSS (Camera Subsystem),
> including CSID and CSIPHY components, to support C-PHY mode configuration.

Awesome to see this actually working after so much time and prior effort!
> 
> # Background and motivation
> 
> Modern smartphone cameras increasingly rely on MIPI C-PHY rather than D-PHY,
> thanks to its higher data throughput and signal efficiency. As a result,
> many OEMs adopt C-PHY interfaces for main (rear) cameras on Qualcomm-based
> devices.
> 
> Until now, mainline Linux lacked C-PHY configuration support for Qualcomm
> chipsets, preventing bring-up of primary camera sensors on several
> Snapdragon platforms. This series closes that gap.

I think it's worth being clearer here that this is only tested on 
SDM845, and will only work on sdm845 anyway because of the lane 
configuration.

Additionally, with Luca's explicit D-phy check removed, other platforms 
won't error out if someone tries to use c-phy without adding the lane 
configuration (and whatever other configuration might also be needed), 
so it might be worth adding a proper check for that.
> 
>   - Introduces C-PHY configuration support for the CAMSS driver stack,
>     covering both CSID and CSIPHY blocks.
>   - Successfully enables C-PHY operation on the Snapdragon 845 platform.
>   - Tested on OnePlus 6 and 6T phones running mainline Linux,
>     using the Sony IMX519 main camera sensor.
>   - The new configuration allows other chipsets versionsto enable C-PHY by
>     simply adding corresponding sensor driver support and csiphy
>     initialization data, following the example set for sdm845.
> 
> With this patch series, mainline Linux gains working C-PHY support for
> Snapdragon 845, paving the way for improved main camera functionality
> across many Qualcomm-based devices. The groundwork also simplifies
> future enablement efforts for additional SoCs and sensors.

woohoo!

Kind regards,
Casey (she/they)

> 
> Signed-off-by: David Heidelberg <david@...t.cz>
> ---
> Casey Connolly (1):
>        media: qcom: camss: csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 CPHY init
> 
> David Heidelberg (6):
>        media: qcom: camss: csiphy: Introduce C-PHY
>        media: qcom: camss: csiphy-3ph: Use odd bits for configuring C-PHY lanes
>        media: qcom: camss: Prepare CSID for C-PHY support
>        media: qcom: camss: csiphy-3ph: Use sdm845 C-PHY configuration sequence
>        media: qcom: camss: Account for C-PHY when calculating link frequency
>        media: qcom: camss: Remove D-PHY-only endpoint restriction
> 
> Petr Hodina (1):
>        media: qcom: camss: Initialize lanes after lane configuration is available
> 
>   .../media/platform/qcom/camss/camss-csid-gen2.c    |   1 +
>   drivers/media/platform/qcom/camss/camss-csid.c     |   3 +-
>   drivers/media/platform/qcom/camss/camss-csid.h     |   1 +
>   .../platform/qcom/camss/camss-csiphy-3ph-1-0.c     | 165 ++++++++++++++++-----
>   drivers/media/platform/qcom/camss/camss-csiphy.c   |   6 +-
>   drivers/media/platform/qcom/camss/camss-csiphy.h   |   2 +
>   drivers/media/platform/qcom/camss/camss.c          |  24 ++-
>   drivers/media/platform/qcom/camss/camss.h          |   2 +-
>   8 files changed, 146 insertions(+), 58 deletions(-)
> ---
> base-commit: 9c0826a5d9aa4d52206dd89976858457a2a8a7ed
> change-id: 20251109-qcom-cphy-bb8cbda1c644
> 
> Best regards,