linux-kernel - [PATCH 1/8] dt-bindings: display: ti,am65x-dss: Add port properties for DSS

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Date:   Tue, 19 Jul 2022 13:38:38 +0530
From:   Aradhya Bhatia <a-bhatia1@...com>
To:     Tomi Valkeinen <tomba@...nel.org>, Jyri Sarha <jyri.sarha@....fi>,
        Rob Herring <robh+dt@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
CC:     Darren Etheridge <detheridge@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Rahul T R <r-ravikumar@...com>,
        Krunal Bhargav <k-bhargav@...com>,
        Devarsh Thakkar <devarsht@...com>,
        DRI Development List <dri-devel@...ts.freedesktop.org>,
        Devicetree List <devicetree@...r.kernel.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/8] dt-bindings: display: ti,am65x-dss: Add port properties for DSS

Add "ti,oldi-mode" property to indicate the tidss driver the OLDI output
mode. The 2 OLDI TXes on am625-dss allow a 3 different types of panel
connections with the board.

1. Single Link / Single Mode on OLDI TX 0 OR 1.
2. Single Link / Duplicate Mode on OLDI TX 0 and 1.
3. Dual Link / Single Mode on OLDI TX 0 and 1.

Add "ti,rgb565-to-888" property to override 16bit output from a videoport
for a bridge that only accepts 24bit RGB888 DPI input.

On some boards the HDMI bridge takes a 24bit DPI input, but only 16 data
pins are actually enabled from the SoC.  This new property forces the
output to be RGB565 on a specific video port if the bridge requests a
24bit RGB color space.

This assumes that the video port is connected like so:

SoC : Bridge
R0 ->   R3
R1 ->   R4
R2 ->   R5
R3 ->   R6
R4 ->   R7
G0 ->   G2
G1 ->   G3
G2 ->   G4
G3 ->   G5
G4 ->   G6
G5 ->   G7
B0 ->   B3
B1 ->   B4
B2 ->   B5
B3 ->   B6
B4 ->   B7

On the bridge side R0->R2, G0->G1, B0->B2 would be tied to ground.
The bridge sees 24bits of data,  but the lsb's are always zero.

Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
---
 .../bindings/display/ti/ti,am65x-dss.yaml     | 25 +++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
index 6bbce921479d..11d9b3821409 100644
--- a/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
+++ b/Documentation/devicetree/bindings/display/ti/ti,am65x-dss.yaml
@@ -80,15 +80,35 @@ properties:
 
     properties:
       port@0:
-        $ref: /schemas/graph.yaml#/properties/port
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
         description:
           The DSS OLDI output port node form video port 1
 
+        properties:
+          ti,oldi-mode:
+            description: TI specific property to indicate the mode the OLDI TXes
+              and the display panel are connected in.
+              0 -> OLDI TXes OFF (driver default for am625-dss)
+              1 -> Single link, Single Mode (OLDI0) (driver default for am65x-dss)
+              2 -> Single link, Single Mode (OLDI1)
+              3 -> Single link, Duplicate Mode
+              4 -> Dual link (Only Single Mode)
+            $ref: /schemas/types.yaml#/definitions/uint32
+            enum: [0, 1, 2, 3, 4]
+
       port@1:
-        $ref: /schemas/graph.yaml#/properties/port
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
         description:
           The DSS DPI output port node from video port 2
 
+        properties:
+          ti,rgb565-to-888:
+            description:
+              property to override DPI output to 16bit for 24bit bridge
+            type: boolean
+
   ti,am65x-oldi-io-ctrl:
     $ref: "/schemas/types.yaml#/definitions/phandle"
     description:
@@ -144,6 +164,7 @@ examples:
                     #size-cells = <0>;
                     port@0 {
                             reg = <0>;
+                            ti,oldi-mode = <1>;
                             oldi_out0: endpoint {
                                     remote-endpoint = <&lcd_in0>;
                             };
-- 
2.37.0