Hi Marek,
Am Dienstag, 25. Juni 2024, 14:05:14 CEST schrieb 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@xxxxxxx>
> ---
> Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> Cc: Conor Dooley <conor+dt@xxxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> Cc: Jonas Karlman <jonas@xxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzk+dt@xxxxxxxxxx>
> Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Robert Foss <rfoss@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: kernel@xxxxxxxxxxxxxxxxxx
> ---
> 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@0
>
I get this warning:
> mx8mp-tqma8mpql-mba8mpxl.dtb: bridge@f: ports:port@2:endpoint: Unevaluated
> properties are not allowed ('toshiba,pre-emphasis' was unexpected)
DT node looks like this:
port@2 {
reg = <2>;
endpoint {
toshiba,pre-emphasis = /bits/ 8 <1 1>;
};
};
I think you are missing this change as well:
-- 8< --
--- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
@@ -92,7 +92,8 @@ properties:
reference to a valid DPI output or input endpoint node.
port@2:
- $ref: /schemas/graph.yaml#/properties/port
+ $ref: /schemas/graph.yaml#/$defs/port-base
+ unevaluatedProperties: false
description: |
eDP/DP output port. The remote endpoint phandle should be a
reference to a valid eDP panel input endpoint node. This port is
-- 8< --
How would you determine the values to be set here? I suspect it's the value
from register DP0_SnkLTChReq (0x6d4) after link training. Are they dependent
on the actual display to be attached?
Best regards,
Alexander
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