[PATCH v3 1/2] dt-bindings: display: bridge: tc358867: Document default DP preemphasis

[Marek Vasut]

Document default DP port preemphasis configurable via new DT property
"toshiba,pre-emphasis". This is useful in case the DP link properties
are known and starting link training from preemphasis setting of 0 dB
is not useful. The preemphasis can be set separately for both DP lanes
in range 0=0dB, 1=3.5dB, 2=6dB .

This is an endpoint property, not a port property, because the TC9595
datasheet does mention that the DP might operate in some sort of split
mode, where each DP lane is used to feed one display, so in that case
there might be two endpoints.

Signed-off-by: Marek Vasut <marex at denx.de>
---
Cc: Andrzej Hajda <andrzej.hajda at intel.com>
Cc: Conor Dooley <conor+dt at kernel.org>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: David Airlie <airlied at gmail.com>
Cc: Jernej Skrabec <jernej.skrabec at gmail.com>
Cc: Jonas Karlman <jonas at kwiboo.se>
Cc: Krzysztof Kozlowski <krzk+dt at kernel.org>
Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
Cc: Lucas Stach <l.stach at pengutronix.de>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Neil Armstrong <neil.armstrong at linaro.org>
Cc: Rob Herring <robh at kernel.org>
Cc: Robert Foss <rfoss at kernel.org>
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: devicetree at vger.kernel.org
Cc: dri-devel at lists.freedesktop.org
Cc: kernel at dh-electronics.com
---
V2: - Fix the type to u8 array
    - Fix the enum items to match what they represent
V3: - Update commit message, expand on this being an endpoint property
---
 .../display/bridge/toshiba,tc358767.yaml       | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
index 2ad0cd6dd49e0..9490854c22f3b 100644
--- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
@@ -98,6 +98,24 @@ properties:
             reference to a valid eDP panel input endpoint node. This port is
             optional, treated as DP panel if not defined
 
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+            properties:
+              toshiba,pre-emphasis:
+                description:
+                  Display port output Pre-Emphasis settings for both DP lanes.
+                $ref: /schemas/types.yaml#/definitions/uint8-array
+                minItems: 2
+                maxItems: 2
+                items:
+                  enum:
+                    - 0 # No pre-emphasis
+                    - 1 # 3.5dB pre-emphasis
+                    - 2 # 6dB pre-emphasis
+
     oneOf:
       - required:
           - port at 0
-- 
2.43.0