[PATCH 1/2] dt-bindings: mmc: amlogic,meson-gx-mmc: add amlogic,core-phase-degrees

[christian . koever-draxl]

From: Christian Stefan Kövér-Draxl <ckoever@xxxxxxxxxx>

The controller samples with a core clock phase that is fixed at 180
degrees in the driver. Some boards need another phase to work at high
speed: an SD slot on an S905W2 TV box fails with CRC errors at 50 MHz
at 180 degrees but works reliably at 270 degrees, which is also what
the vendor kernel programs for it.

Add an optional property to describe the phase.

Signed-off-by: Christian Stefan Kövér-Draxl <ckoever@xxxxxxxxxx>
---
 .../devicetree/bindings/mmc/amlogic,meson-gx-mmc.yaml    | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/amlogic,meson-gx-mmc.yaml b/Documentation/devicetree/bindings/mmc/amlogic,meson-gx-mmc.yaml
index 976f36de2091..8123375a66e0 100644
--- a/Documentation/devicetree/bindings/mmc/amlogic,meson-gx-mmc.yaml
+++ b/Documentation/devicetree/bindings/mmc/amlogic,meson-gx-mmc.yaml
@@ -58,6 +58,15 @@ properties:
   power-domains:
     maxItems: 1
 
+  amlogic,core-phase-degrees:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Phase of the controller core clock relative to the card clock. Some
+      boards only sample reliably at high speed with a phase other than
+      the default.
+    enum: [0, 90, 180, 270]
+    default: 180
+
 required:
   - compatible
   - reg
-- 
2.56.0