Hi Paul,
On Wed, Mar 09, 2022 at 03:32:00PM +0100, Paul Kocialkowski wrote:
While bridge/panel detection was initially relying on the usual port/ports-based of graph detection, it was recently changed to perform the lookup on any child node that is not port/ports instead when such a node is available, with no fallback on the usual way.
This results in breaking detection when a child node is present but does not contain any panel or bridge node, even when the usual port/ports-based of graph is there.
In order to support both situations properly, this commit reworks the logic to try both options and not just one of the two: it will only return -EPROBE_DEFER when both have failed.
Signed-off-by: Paul Kocialkowski paul.kocialkowski@bootlin.com Fixes: 80253168dbfd ("drm: of: Lookup if child node has panel or bridge")
Thanks, it's in pretty good shape now, but I have a few bike sheds to paint :)
drivers/gpu/drm/drm_of.c | 93 +++++++++++++++++++++------------------- 1 file changed, 49 insertions(+), 44 deletions(-)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index 9d90cd75c457..67f1b7dfc892 100644 --- a/drivers/gpu/drm/drm_of.c +++ b/drivers/gpu/drm/drm_of.c @@ -219,6 +219,35 @@ int drm_of_encoder_active_endpoint(struct device_node *node, } EXPORT_SYMBOL_GPL(drm_of_encoder_active_endpoint);
+static int drm_of_find_remote_panel_or_bridge(struct device_node *remote,
struct drm_panel **panel,struct drm_bridge **bridge)
This function performs its look up directly on the struct device_node passed as argument, so I don't think the "remote" in the name is great. Since it's static, we can just call it find_panel_or_bridge, what do you think?
+{
- int ret = -EPROBE_DEFER;
- if (panel) {
*panel = of_drm_find_panel(remote);if (!IS_ERR(*panel))ret = 0;
return 0?
else*panel = NULL;- }
- /* No panel found yet, check for a bridge next. */
- if (bridge) {
if (ret) {
And the return above allows to remove that test
*bridge = of_drm_find_bridge(remote);if (*bridge)ret = 0;
return 0?
} else {*bridge = NULL;}- }
- return ret;
And here we can just return -EPROBE_DEFER
+}
/**
- drm_of_find_panel_or_bridge - return connected panel or bridge device
- @np: device tree node containing encoder output ports
@@ -249,57 +278,33 @@ int drm_of_find_panel_or_bridge(const struct device_node *np, if (panel) *panel = NULL;
- /**
* 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;goto of_find_panel_or_bridge;
- /* Check for a graph on the device node first. */
- if (of_graph_is_present(np)) {
remote = of_graph_get_remote_node(np, port, endpoint);if (remote) {ret = drm_of_find_remote_panel_or_bridge(remote, panel,bridge);of_node_put(remote);}
- /*
* 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;
- /* Otherwise check for any child node other than port/ports. */
- if (ret) {
for_each_available_child_of_node(np, remote) {if (of_node_name_eq(remote, "port") ||of_node_name_eq(remote, "ports"))continue;
- if (panel) {
*panel = of_drm_find_panel(remote);if (!IS_ERR(*panel))ret = 0;else*panel = NULL;- }
ret = drm_of_find_remote_panel_or_bridge(remote, panel,bridge);of_node_put(remote);
- /* 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)break;
}
of_node_put(remote); return ret;
}
So the diff is fairly hard to read, but it ends up as:
int ret = -EPROBE_DEFER; struct device_node *remote; if (!panel && !bridge) return -EINVAL; if (panel) *panel = NULL; /* Check for a graph on the device node first. */ if (of_graph_is_present(np)) { remote = of_graph_get_remote_node(np, port, endpoint); if (remote) { ret = drm_of_find_remote_panel_or_bridge(remote, panel, bridge); of_node_put(remote);
I think we can simplify this by doing
if (!ret) return ret;
} } /* Otherwise check for any child node other than port/ports. */ if (ret) {
And thus we won't have to check for ret here
for_each_available_child_of_node(np, remote) {
I'm a bit reluctant with variables that we reuse from one loop to another, especially since it's a bit misleading here. What about using a (loop local) remote variable in the of_graph path, and a loop-local variable node or child here?
if (of_node_name_eq(remote, "port") || of_node_name_eq(remote, "ports")) continue; ret = drm_of_find_remote_panel_or_bridge(remote, panel, bridge); of_node_put(remote); /* Stop at the first found occurrence. */ if (!ret) break;
Ditto, let's just return here
} } return ret;
And then we can just return EPROBE_DEFER here (and get rid of ret entirely)
Maxime