Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] The `no-hpd` property is documented in the device tree bindings but has no corresponding implementation in the driver. --
--- Patch [1]: [PATCH v5 1/2] dt-bindings: display: bridge: cdns, mhdp8546: Add no-hpd property to the cadence bridge --- commit 4ac60fbbcafba148711703269045306014cd935a Author: Rahul T R <[email protected]> dt-bindings: display: bridge: cdns, mhdp8546: Add no-hpd property to the cadence bridge This commit introduces the no-hpd property to the mhdp8546 device tree bindings. It provides a way to indicate when the hardware HPD line is not available, specifying that the driver should fall back to auxiliary channel DPCD reads for hotplug detection. > diff --git > a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml > b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml > --- a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml > +++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8546.yaml [ ... ] > @@ -57,6 +57,23 @@ properties: > interrupts: > maxItems: 1 > > + no-hpd: > + type: boolean > + description: > + Set if the HPD line on the bridge isn't physically connected to the > + DisplayPort connector or cannot be used for hotplug detection. > + > + Valid use cases include: > + - HPD pin not routed to the connector on the PCB > + - HPD signal muxed with another function (e.g., audio) on the SoC, > + making it unavailable for hotplug detection > + - Hardware design where HPD cannot reliably detect monitor presence > + > + When this property is set, the driver will use auxiliary channel (AUX) > + DPCD reads to detect monitor connection instead of relying on the > + hardware HPD signal. Monitor detection will use polling rather than > + interrupt-driven detection. > + [Severity: Medium] Is the driver implementation missing for this new property? The binding documentation states that the driver will use polling rather than interrupt-driven detection when this property is set. However, looking at the driver in cdns_mhdp_probe(), it unconditionally requires hardware HPD operations: drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c:cdns_mhdp_probe() { ... mhdp->bridge.of_node = pdev->dev.of_node; mhdp->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD; mhdp->bridge.type = DRM_MODE_CONNECTOR_DisplayPort; ... } Does the driver need logic to parse the no-hpd property and conditionally adjust these operations to enable polling instead of enforcing hardware HPD? > ports: > $ref: /schemas/graph.yaml#/properties/ports > -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
