[PATCH 2/4] dt-bindings: mmc: spacemit,sdhci: Add tx delay property

[Yixun Lan]

From: Long Wan <long.wan at linux.spacemit.com>

Introduce a vendor specific property to configure the step count of TX
delay line which should be applied before RX tuning, compensating for
board level trace differences. The TX delay line result comes from test
out of real board which vary from different hardware layout.

Signed-off-by: Long Wan <long.wan at linux.spacemit.com>
Signed-off-by: Yixun Lan <dlan at kernel.org>
---
 Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml b/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
index f35bf7ce08dd..3399a2d076dc 100644
--- a/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
+++ b/Documentation/devicetree/bindings/mmc/spacemit,sdhci.yaml
@@ -63,6 +63,16 @@ properties:
   pinctrl-1:
     description: Optional pinctrl state for 1.8V UHS operation with "uhs" name
 
+  spacemit,tx-delay:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 255
+    description:
+      TX delay line setting applied before RX tuning, compensating for
+      board level trace differences. This is a delay line step count with
+      no fixed time-per-step conversion; determined empirically per board
+      specific, used on SD/SDIO hosts.
+
 required:
   - compatible
   - reg

-- 
2.55.0