Unverified Commit 169466d4 authored by Bjorn Andersson's avatar Bjorn Andersson Committed by Maxime Ripard
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Revert "drm: of: Properly try all possible cases for bridge/panel detection" 



Commit '80253168 ("drm: of: Lookup if child node has panel or
bridge")' introduced the ability to describe a panel under a display
controller without having to use a graph to connect the controller to
its single child panel (or bridge).

The implementation of this would find the first non-graph node and
attempt to acquire the related panel or bridge. This prevents cases
where any other child node, such as a aux bus for a DisplayPort
controller, or an opp-table to find the referenced panel.

Commit '67bae5f2 ("drm: of: Properly try all possible cases for
bridge/panel detection")' attempted to solve this problem by not
bypassing the graph reference lookup before attempting to find the panel
or bridge.

While this does solve the case where a proper graph reference is
present, it does not allow the caller to distinguish between a
yet-to-be-probed panel or bridge and the absence of a reference to a
panel.

One such case is a DisplayPort controller that on some boards have an
explicitly described reference to a panel, but on others have a
discoverable DisplayPort display attached (which doesn't need to be
expressed in DeviceTree).

This reverts commit '67bae5f2 ("drm: of: Properly try all possible
cases for bridge/panel detection")', as a step towards reverting commit
'80253168 ("drm: of: Lookup if child node has panel or bridge")'.

Signed-off-by: default avatarBjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: default avatarPaul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: default avatarMaxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220420231230.58499-1-bjorn.andersson@linaro.org
parent 3d0b93d9

drivers/gpu/drm/drm_of.c

+49 −50
Original line number Diff line number Diff line
@@ -214,29 +214,6 @@ int drm_of_encoder_active_endpoint(struct device_node *node, 
}

EXPORT_SYMBOL_GPL(drm_of_encoder_active_endpoint);



static int find_panel_or_bridge(struct device_node *node,

				struct drm_panel **panel,

				struct drm_bridge **bridge)

{

	if (panel) {

		*panel = of_drm_find_panel(node);

		if (!IS_ERR(*panel))

			return 0;



		/* Clear the panel pointer in case of error. */

		*panel = NULL;

	}



	/* No panel found yet, check for a bridge next. */

	if (bridge) {

		*bridge = of_drm_find_bridge(node);

		if (*bridge)

			return 0;

	}



	return -EPROBE_DEFER;

}



/**

 * drm_of_find_panel_or_bridge - return connected panel or bridge device

 * @np: device tree node containing encoder output ports
@@ -259,44 +236,66 @@ int drm_of_find_panel_or_bridge(const struct device_node *np, 
				struct drm_panel **panel,

				struct drm_bridge **bridge)

{

	struct device_node *node;

	int ret;

	int ret = -EPROBE_DEFER;

	struct device_node *remote;



	if (!panel && !bridge)

		return -EINVAL;



	if (panel)

		*panel = NULL;

	if (bridge)

		*bridge = NULL;



	/* Check for a graph on the device node first. */

	if (of_graph_is_present(np)) {

		node = of_graph_get_remote_node(np, port, endpoint);

		if (node) {

			ret = find_panel_or_bridge(node, panel, bridge);

			of_node_put(node);

	/**

	 * Devices can also be child nodes when we also control that device

	 * through the upstream device (ie, MIPI-DCS for a MIPI-DSI device).

	 *

	 * Lookup for a child node of the given parent that isn't either port

	 * or ports.

	 */

	for_each_available_child_of_node(np, remote) {

		if (of_node_name_eq(remote, "port") ||

		    of_node_name_eq(remote, "ports"))

			continue;



			if (!ret)

				return 0;

		}

		goto of_find_panel_or_bridge;

	}



	/* Otherwise check for any child node other than port/ports. */

	for_each_available_child_of_node(np, node) {

		if (of_node_name_eq(node, "port") ||

		    of_node_name_eq(node, "ports"))

			continue;

	/*

	 * of_graph_get_remote_node() produces a noisy error message if port

	 * node isn't found and the absence of the port is a legit case here,

	 * so at first we silently check whether graph presents in the

	 * device-tree node.

	 */

	if (!of_graph_is_present(np))

		return -ENODEV;



		ret = find_panel_or_bridge(node, panel, bridge);

		of_node_put(node);

	remote = of_graph_get_remote_node(np, port, endpoint);



		/* Stop at the first found occurrence. */

		if (!ret)

			return 0;

of_find_panel_or_bridge:

	if (!remote)

		return -ENODEV;



	if (panel) {

		*panel = of_drm_find_panel(remote);

		if (!IS_ERR(*panel))

			ret = 0;

		else

			*panel = NULL;

	}



	return -EPROBE_DEFER;

	/* No panel found yet, check for a bridge next. */

	if (bridge) {

		if (ret) {

			*bridge = of_drm_find_bridge(remote);

			if (*bridge)

				ret = 0;

		} else {

			*bridge = NULL;

		}



	}



	of_node_put(remote);

	return ret;

}

EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);