[PATCH v2 1/2] dt-bindings: ufs: Document static TX Equalization settings properties

[Can Guo]

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

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

Add vendor-neutral DT patternProperties:
txeq-settings-g[1-6]

Each property is a uint32 array of per-lane tuples:
(PreShoot, DeEmphasis, PrecodeEn)

Tuple order is:
Host Lane 0, [Host Lane 1], Device Lane 0, [Device Lane 1]

Accept 2..4 tuples (6..12 u32 values) to cover x1/x2 lane configs. These
patternProperties carry board-level SI characterization data used as
static TX Equalization settings for each High Speed Gear.

Signed-off-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
---
 Documentation/devicetree/bindings/ufs/ufs-common.yaml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/ufs/ufs-common.yaml b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
index ed97f5682509..bc83948fc168 100644
--- a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
+++ b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
@@ -105,6 +105,17 @@ properties:
       Restricts the UFS controller to rate-a or rate-b for both TX and
       RX directions.
 
+patternProperties:
+  "^txeq-settings-g[1-6]$":
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 6
+    maxItems: 12
+    description: |
+      Static TX Equalization settings for High Speed (HS) gears.
+      The settings are specified as an array of tuples (PreShoot, DeEmphasis, PrecodeEn).
+      The array must contain these tuples in the following order:
+      Host Lane 0, [Host Lane 1], Device Lane 0, [Device Lane 1].
+
 dependencies:
   freq-table-hz: [ clocks ]
   operating-points-v2: [ clocks, clock-names ]
-- 
2.34.1