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Revert "drm: of: Properly try all possible cases for bridge/panel detection"

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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@linaro.org>
Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220420231230.58499-1-bjorn.andersson@linaro.org
This commit is contained in:
Bjorn Andersson 2022-04-20 16:12:29 -07:00 committed by Maxime Ripard
parent 3d0b93d92a
commit 169466d4e5
No known key found for this signature in database
GPG key ID: E3EF0D6F671851C5
1 changed files with 50 additions and 51 deletions
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101
drivers/gpu/drm/drm_of.c
View file

@ -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);
/* Stop at the first found occurrence. */
if (!ret)
return 0;
goto of_find_panel_or_bridge;
}
return -EPROBE_DEFER;
/*
* 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;
}
}
of_node_put(remote);
return ret;
}
EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);