Commit '80253168dbfd ("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 '67bae5f28c89 ("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 '67bae5f28c89 ("drm: of: Properly try all possible
cases for bridge/panel detection")', as a step towards reverting commit
'80253168dbfd ("drm: of: Lookup if child node has panel or bridge")'.
Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---
drivers/gpu/drm/drm_of.c | 99 ++++++++++++++++++++--------------------
1 file changed, 49 insertions(+), 50 deletions(-)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index f4df344509a8..026e4e29a0f3 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -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);
-
- if (!ret)
- return 0;
- }
- }
- /* 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"))
+ /**
+ * 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;
- ret = find_panel_or_bridge(node, panel, bridge);
- of_node_put(node);
+ goto of_find_panel_or_bridge;
+ }
+
+ /*
+ * 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;
+
+ remote = of_graph_get_remote_node(np, port, endpoint);
+
+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;
+ }
+
+ /* 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;
+ }
- /* Stop at the first found occurrence. */
- if (!ret)
- return 0;
}
- return -EPROBE_DEFER;
+ of_node_put(remote);
+ return ret;
}
EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);
--
2.35.1
