Thread (17 messages) 17 messages, 4 authors, 2025-09-01
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Revisions (6)
  1. v1 [diff vs current]
  2. v2 [diff vs current]
  3. v3 current
  4. v4 [diff vs current]
  5. v5 [diff vs current]
  6. v6 [diff vs current]

[PATCH V3 0/4] Add DT-based gear and rate limiting support

From: Ram Kumar Dwivedi <hidden>
Date: 2025-08-26 15:09:33
Also in: linux-arm-msm, linux-scsi, lkml

From: Ram Kumar Dwivedi <redacted>

This patch series adds support for limiting the maximum high-speed
gear and rate used by the UFS controller via device tree properties.

Some platforms may have signal integrity, clock configuration, or
layout issues that prevent reliable operation at higher gears or rates.
This is especially critical in automotive and other platforms where
stability is prioritized over peak performance.

The series follows this logical progression:
1. Document the new DT properties in the common UFS binding
2. Clean up existing redundant code in the qcom driver
3. Add platform-level parsing support for the new properties
4. Integrate the platform support in the qcom driver

This approach makes the functionality available to other UFS host
drivers and provides a cleaner, more maintainable implementation.

Changes from V1:
- Restructured patch series for better logical flow and maintainability.
- Moved DT bindings to ufs-common.yaml making it available for all UFS
  controllers.
- Added platform-level support in ufshcd-pltfrm.c for code reusability.
- Separated the cleanup patch to remove redundant hs_rate assignment in
  qcom driver.
- Removed SA8155 DTS changes to keep the series focused on core
  functionality.
- Improved commit messages with better technical rationale.

Changes from V2:
- Documented default values of limit-rate and limit-hs-gear in DT bindings
  as per Krzysztof's suggestion.

Ram Kumar Dwivedi (4):
  ufs: dt-bindings: Document gear and rate limit properties
  ufs: ufs-qcom: Remove redundant re-assignment to hs_rate
  ufs: pltfrm: Allow limiting HS gear and rate via DT
  ufs: ufs-qcom: Add support for limiting HS gear and rate

 .../devicetree/bindings/ufs/ufs-common.yaml   | 18 ++++++++++++
 drivers/ufs/host/ufs-qcom.c                   | 21 ++++++++++----
 drivers/ufs/host/ufshcd-pltfrm.c              | 29 +++++++++++++++++++
 drivers/ufs/host/ufshcd-pltfrm.h              |  1 +
 4 files changed, 63 insertions(+), 6 deletions(-)

-- 
2.50.1
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