Note: WIP tag added, as not everything from the previous review round has
been addressed.

# Short summary

This patch series extends the Qualcomm CAMSS (Camera Subsystem),
including CSID and CSIPHY components, to support C-PHY mode configuration.

# 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.

 - 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.

Until merged, the series will be also available at:
  https://codeberg.org/sdm845/linux/commits/branch/b4/qcom-cphy

Signed-off-by: David Heidelberg <david@ixit.cz>
---
Changes in v5:
- Split first patch enabling C-PHY part into last patch. (Bryan)
- Fix the camss_get_link_freq crash. (Cory)
- Dropped patch whitelisting C-PHY, instead use nullptr check. (Bryan)
- Dropped A-b/R-b from
 "media: qcom: camss: Initialize lanes after lane configuration is available"
 and changed Petr to Co-developed by and owned the patch.
- Link to v4: https://lore.kernel.org/r/20260301-qcom-cphy-v4-0-e53316d2cc65@ixit.cz

Changes in v4:
- Documented cphy parametr to camss_get_link_freq.
- Use BIT() macro for lane_mask. (Bryan)
- Correct lane_mask calculation. (Kieran + me)
- Removed comment for the D/C-PHY sequences init. (Bryan)
- Pass &csid->phy for calculate freq. (Bryan)
- Added missing cphy description to camss_get_link_freq. (kernel test robot)
- Gen2 v1.1 MIPI CSI-2 CPHY init hex to lowercase.
- Added back missed commit with improved electrical for sdm845 3ph.
- NOT addressed yet:
  - Proliferating special cases in switch statements on a per-SoC basis is verboten. 
  - is it possible to set clock_lane to say 0xff in DT ? 
- Link to v3: https://lore.kernel.org/r/20260117-qcom-cphy-v3-0-8ce76a06f7db@ixit.cz

Changes in v3:
- Make lanes_enable return sucess or error, since I couldn't move the
  configuration to the _init.
- Dropped R-b tags on
  "media: qcom: camss: Initialize lanes after lane configuration is available"
  as I changed formatting.
- Link to v2: https://lore.kernel.org/r/20251204-qcom-cphy-v2-0-6b35ef8b071e@ixit.cz

Changes in v2:
- This is still WIP patch series, thus I wanted to publish already
  changed parts to get feedback regarding to the direction of patchset.
- When switch to using odd bits, zeroed val which was left unitialized in v1.
- Accidentally missed archs added back in the commit moving lane regs to
  new location.
- Remove commit with reverting check for only D-PHY is supported and
  adjusted the check to also account for C-PHY.
- Documented link frequency calculation with defines. (Casey)
- Changed the cphy boolean to phy_cfg enum in the camss/camss-csiphy.
  (Brian)
- Added patch for csiphy-3ph enablement for sm7280 from Luca as I'm
  meanwhile trying to bring up the C-PHY sensor on FairPhone 5.
- Merged these two commits together
    csiphy-3ph: Enable sdm845 C-PHY sequence
    csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 CPHY init
  merged R-b.
- Link to v1: https://lore.kernel.org/r/20251109-qcom-cphy-v1-0-165f7e79b0e1@ixit.cz

---
Casey Connolly (1):
      media: qcom: camss: csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 C-PHY init

David Heidelberg (7):
      media: qcom: camss: csiphy: Introduce PHY configuration
      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: Initialize lanes after lane configuration is available
      media: qcom: camss: csiphy-3ph: Update Gen2 v1.1 MIPI CSI-2 C-PHY init
      media: qcom: camss: Account for C-PHY when calculating link frequency
      media: qcom: camss: Enable C-PHY where available

Luca Weiss (1):
      media: qcom: camss: csiphy-3ph: Add Gen2 v1.2.1 MIPI CSI-2 C-PHY init

 .../media/platform/qcom/camss/camss-csid-gen2.c    |   1 +
 drivers/media/platform/qcom/camss/camss-csid.c     |   8 +-
 drivers/media/platform/qcom/camss/camss-csid.h     |   1 +
 .../platform/qcom/camss/camss-csiphy-2ph-1-0.c     |   8 +-
 .../platform/qcom/camss/camss-csiphy-3ph-1-0.c     | 355 ++++++++++++++++++---
 drivers/media/platform/qcom/camss/camss-csiphy.c   |  11 +-
 drivers/media/platform/qcom/camss/camss-csiphy.h   |   8 +-
 drivers/media/platform/qcom/camss/camss.c          |  36 ++-
 drivers/media/platform/qcom/camss/camss.h          |   2 +-
 9 files changed, 355 insertions(+), 75 deletions(-)
---
base-commit: e7d700e14934e68f86338c5610cf2ae76798b663
change-id: 20251109-qcom-cphy-bb8cbda1c644

Best regards,
-- 
David Heidelberg <david@ixit.cz>

On 31/05/2026 14:08, David Heidelberg via B4 Relay wrote:
> Note: WIP tag added, as not everything from the previous review round has
> been addressed.
> 
> # Short summary
> 
> This patch series extends the Qualcomm CAMSS (Camera Subsystem),
> including CSID and CSIPHY components, to support C-PHY mode configuration.
> 
> # 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.
> 
>   - 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.
> 
> Until merged, the series will be also available at:
>    https://codeberg.org/sdm845/linux/commits/branch/b4/qcom-cphy
> 
> Signed-off-by: David Heidelberg <david@ixit.cz>
> ---
> Changes in v5:
> - Split first patch enabling C-PHY part into last patch. (Bryan)
> - Fix the camss_get_link_freq crash. (Cory)
> - Dropped patch whitelisting C-PHY, instead use nullptr check. (Bryan)
> - Dropped A-b/R-b from
>   "media: qcom: camss: Initialize lanes after lane configuration is available"
>   and changed Petr to Co-developed by and owned the patch.
> - Link to v4: https://lore.kernel.org/r/20260301-qcom-cphy-v4-0-e53316d2cc65@ixit.cz
> 
> Changes in v4:
> - Documented cphy parametr to camss_get_link_freq.
> - Use BIT() macro for lane_mask. (Bryan)
> - Correct lane_mask calculation. (Kieran + me)
> - Removed comment for the D/C-PHY sequences init. (Bryan)
> - Pass &csid->phy for calculate freq. (Bryan)
> - Added missing cphy description to camss_get_link_freq. (kernel test robot)
> - Gen2 v1.1 MIPI CSI-2 CPHY init hex to lowercase.
> - Added back missed commit with improved electrical for sdm845 3ph.
> - NOT addressed yet:
>    - Proliferating special cases in switch statements on a per-SoC basis is verboten.
>    - is it possible to set clock_lane to say 0xff in DT ?
> - Link to v3: https://lore.kernel.org/r/20260117-qcom-cphy-v3-0-8ce76a06f7db@ixit.cz
> 
> Changes in v3:
> - Make lanes_enable return sucess or error, since I couldn't move the
>    configuration to the _init.
> - Dropped R-b tags on
>    "media: qcom: camss: Initialize lanes after lane configuration is available"
>    as I changed formatting.
> - Link to v2: https://lore.kernel.org/r/20251204-qcom-cphy-v2-0-6b35ef8b071e@ixit.cz
> 
> Changes in v2:
> - This is still WIP patch series, thus I wanted to publish already
>    changed parts to get feedback regarding to the direction of patchset.
> - When switch to using odd bits, zeroed val which was left unitialized in v1.
> - Accidentally missed archs added back in the commit moving lane regs to
>    new location.
> - Remove commit with reverting check for only D-PHY is supported and
>    adjusted the check to also account for C-PHY.
> - Documented link frequency calculation with defines. (Casey)
> - Changed the cphy boolean to phy_cfg enum in the camss/camss-csiphy.
>    (Brian)
> - Added patch for csiphy-3ph enablement for sm7280 from Luca as I'm
>    meanwhile trying to bring up the C-PHY sensor on FairPhone 5.
> - Merged these two commits together
>      csiphy-3ph: Enable sdm845 C-PHY sequence
>      csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 CPHY init
>    merged R-b.
> - Link to v1: https://lore.kernel.org/r/20251109-qcom-cphy-v1-0-165f7e79b0e1@ixit.cz
> 
> ---
> Casey Connolly (1):
>        media: qcom: camss: csiphy-3ph: Add Gen2 v1.1 MIPI CSI-2 C-PHY init
> 
> David Heidelberg (7):
>        media: qcom: camss: csiphy: Introduce PHY configuration
>        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: Initialize lanes after lane configuration is available
>        media: qcom: camss: csiphy-3ph: Update Gen2 v1.1 MIPI CSI-2 C-PHY init
>        media: qcom: camss: Account for C-PHY when calculating link frequency
>        media: qcom: camss: Enable C-PHY where available
> 
> Luca Weiss (1):
>        media: qcom: camss: csiphy-3ph: Add Gen2 v1.2.1 MIPI CSI-2 C-PHY init
> 
>   .../media/platform/qcom/camss/camss-csid-gen2.c    |   1 +
>   drivers/media/platform/qcom/camss/camss-csid.c     |   8 +-
>   drivers/media/platform/qcom/camss/camss-csid.h     |   1 +
>   .../platform/qcom/camss/camss-csiphy-2ph-1-0.c     |   8 +-
>   .../platform/qcom/camss/camss-csiphy-3ph-1-0.c     | 355 ++++++++++++++++++---
>   drivers/media/platform/qcom/camss/camss-csiphy.c   |  11 +-
>   drivers/media/platform/qcom/camss/camss-csiphy.h   |   8 +-
>   drivers/media/platform/qcom/camss/camss.c          |  36 ++-
>   drivers/media/platform/qcom/camss/camss.h          |   2 +-
>   9 files changed, 355 insertions(+), 75 deletions(-)
> ---
> base-commit: e7d700e14934e68f86338c5610cf2ae76798b663
> change-id: 20251109-qcom-cphy-bb8cbda1c644
> 
> Best regards,
> --
> David Heidelberg <david@ixit.cz>
> 
> 
> 

It feels to me that the standalone PHY is pretty far alone by now.

Its totally up to you BUT if you are up for the effort and BTW thank you 
for taking personal time to work on this but, how would you feel about 
basing this series on top of the standalone DPHY series ?

---
bod