scsi: ufs: dt-bindings: Document gear and rate limit properties

Add optional "limit-hs-gear" and "limit-rate" properties to the UFS
controller common binding. These properties allow limiting the maximum
HS gear and rate.

This is useful in cases where the customer board may have signal
integrity, clock configuration or layout issues that prevent reliable
operation at higher gears. Such limitations are especially critical in
those platforms, where stability is prioritized over peak performance.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Ram Kumar Dwivedi <quic_rdwivedi@quicinc.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/Documentation/devicetree/bindings/ufs/ufs-common.yaml b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
index 31fe7f30ff5b8d29c3554fa5677ec9bbbe96760d..9f04f34d8c5aa5114a5e00cae674ef1ab9663b17 100644 (file)
--- a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
+++ b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
@@ -89,6 +89,22 @@ properties:
 
   msi-parent: true
 
+  limit-hs-gear:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 6
+    default: 6
+    description:
+      Restricts the maximum HS gear used in both TX and RX directions.
+
+  limit-gear-rate:
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [rate-a, rate-b]
+    default: rate-b
+    description:
+      Restricts the UFS controller to rate-a or rate-b for both TX and
+      RX directions.
+
 dependencies:
   freq-table-hz: [ clocks ]
   operating-points-v2: [ clocks, clock-names ]