[RFC PATCH 1/2] dt-bindings: display: meson-dw-hdmi: add GXLX2 compatible

[Zinan Zhou <zinan@mieulab.com>]

The GXLX2 HDMI transmitter uses the byte-addressed DesignWare controller
registers and directly mapped TOP window also present on G12A. Its display
pipeline and HDMI PHY programming remain GXL-like, however.

Add a dedicated compatible with no fallback. The generic
meson-gx-dw-hdmi interface uses indirect address/data registers and cannot
operate this hardware, while meson-g12a-dw-hdmi would select incompatible
PHY initialization values.

The one-resource representation is proposed for RFC review; DWC and TOP
occupy one contiguous MMIO range on the tested HG680-LC.

Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Zinan Zhou <zinan@mieulab.com>
---
 .../devicetree/bindings/display/amlogic,meson-dw-hdmi.yaml | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/amlogic,meson-dw-hdmi.yaml b/Documentation/devicetree/bindings/display/amlogic,meson-dw-hdmi.yaml
index 416fe263ac92..4a17eccabea9 100644
--- a/Documentation/devicetree/bindings/display/amlogic,meson-dw-hdmi.yaml
+++ b/Documentation/devicetree/bindings/display/amlogic,meson-dw-hdmi.yaml
@@ -29,8 +29,10 @@ description: |
   The HDMI TOP block only supports HPD sensing.
   The Synopsys HDMI Controller interrupt is routed through the
   TOP Block interrupt.
-  Communication to the TOP Block and the Synopsys HDMI Controller is done
-  via a pair of dedicated addr+read/write registers.
+  Communication with the TOP Block and the Synopsys HDMI Controller uses a pair
+  of dedicated address/data registers on GXBB, GXL and GXM. GXLX2 and G12A
+  instead expose byte-addressed controller registers and a directly mapped TOP
+  window.
   The HDMI PHY is configured by registers in the HHI register block.
 
   Pixel data arrives in "4:4:4" format from the VENC block and the VPU HDMI mux
@@ -54,6 +56,7 @@ properties:
               - amlogic,meson-gxm-dw-hdmi # GXM (S912)
           - const: amlogic,meson-gx-dw-hdmi
       - enum:
+          - amlogic,meson-gxlx2-dw-hdmi # GXLX2 (S905L3)
           - amlogic,meson-g12a-dw-hdmi # G12A (S905X2, S905Y2, S905D2)
 
   reg:
-- 
2.43.0