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Merge patch series "scsi: ufs: Add support for static TX Equalization settings"

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Can Guo <can.guo@oss.qualcomm.com> says:

Hi,

This series adds support for board-specific static TX Equalization settings
provided through Device Tree.

This series is based on the earlier TX Equalization enablement work and
persistent storage/retrieval of optimal TX Equalization settings work:
https://lore.kernel.org/all/20260325152154.1604082-1-can.guo@oss.qualcomm.com
https://lore.kernel.org/all/20260424151420.111675-1-can.guo@oss.qualcomm.com

Background
==========

UFS v5.0/UFSHCI v5.0 adds HS-G6 support (46.6 Gbps/lane) via UniPro v3.0
and M-PHY v6.0. These specs define TX Equalization for all High-Speed
Gears (not only HS-G6) to compensate channel loss and improve signal
integrity at high speed.

For HS-G6, M-PHY uses PAM4 1b1b line coding. Pre-Coding may also be
required depending on channel characteristics.

This series adds vendor-neutral DT properties:
- patternProperties: txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6]
- fixed property: tx-precode-enable-g6

All properties use per-lane Host/Device tuples and accept 2 or 4 values
for x1/x2 lane configurations:
- txeq-preshoot-g[1-6]: values 0..7
- txeq-deemphasis-g[1-6]: values 0..7
- tx-precode-enable-g6: values 0/1

These properties carry board-level SI characterization data used as static
TX Equalization settings for each High-Speed Gear.

Example DTS snippet
===================

The following x2-lane example shows the expected DT encoding:

	ufs@1d84000 {
		lanes-per-direction = <2>;

		txeq-preshoot-g6 = <1 2>, <3 4>;
		txeq-deemphasis-g6 = <0 1>, <2 3>;
		tx-precode-enable-g6 = <1 0>, <0 1>;
	};

Relationship with Adaptive TX Equalization
==========================================

Adaptive TX Equalization remains the primary path when enabled.

Static TX Equalization settings from DT are board-specific baseline values,
but when adaptive TX Equalization is used, static settings are not final:
- If valid settings are retrieved from qTxEQGnSettings/wTxEQGnSettingsExt,
  those retrieved settings override static DT settings.
- If retrieval is not available/valid, TX EQTR runs and trained settings
  override static DT settings.

So static DT settings are a fallback and are intended for cases where
adaptive TX Equalization is not enabled/used.

No behavior changes for platforms that do not provide these properties.

What this series adds
=====================

1. dt-bindings:
- Document txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6], and
  tx-precode-enable-g6 in ufs-common.yaml.
- Define tuple encoding for host/device values per lane.
- Add per-property value validation ranges in schema.

2. UFS core/platform integration:
- Parse and validate per-gear DT TX EQ settings during platform init.
- Store parsed values into per-gear TX EQ params and track DT origin using
  the from_dt flag.
- Integrate static-state handling in TX EQ flow so DT-provided entries are
  fed through the adaptive TX Equalization path and then converted to
  normal runtime params.

Link: https://patch.msgid.link/20260616113348.1168248-1-can.guo@oss.qualcomm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Martin K. Petersen 2026-07-16 22:16:57 -04:00
commit e700a7c94f
4 changed files with 228 additions and 1 deletions
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