Hi Jagan,
On Wed 02 Feb 22, 21:34, Jagan Teki wrote:
Devices can also be child nodes when we also control that device through the upstream device (ie, MIPI-DCS for a MIPI-DSI device).
drm_of_find_panel_or_bridge can lookup panel or bridge for a given device has port and endpoint and it fails to lookup if the device has a child nodes.
This patch breaks the logicvc drm driver that I'm currently developping. The symptom is that drm_of_find_panel_or_bridge now always returns -EPROBE_DEFER even after the panel has probed and is running well. It seems that the function can no longer find the panel.
I haven't figured out the details, but reverting your patch makes it work again. I suspect other drivers might be affected as well, so it would probably be a good idea to revert the patch until the root cause is clearly understood and the patch can be adapted accordingly.
Here is what the device-tree looks like:
/ { panel: panel-lvds { compatible = "panel-lvds";
[...]
port { #address-cells = <1>; #size-cells = <0>;
panel_input: endpoint@0 { reg = <0>; remote-endpoint = <&logicvc_output>; }; }; }; };
&amba { logicvc: logicvc@43c00000 { compatible = "xylon,logicvc-3.02.a", "syscon", "simple-mfd"; reg = <0x43c00000 0x6000>;
#address-cells = <1>; #size-cells = <1>;
[...]
logicvc_display: display-engine@0 { compatible = "xylon,logicvc-4.01.a-display";
[...]
port { #address-cells = <1>; #size-ce/lls = <0>;
logicvc_output: endpoint@0 { reg = <0>; remote-endpoint = <&panel_input>; }; }; }; }; };
Cheers,
Paul
This patch add support to lookup for a child node of the given parent that isn't either port or ports.
Example OF graph representation of DSI host, which has port but not has ports and has child panel node.
dsi { compatible = "allwinner,sun6i-a31-mipi-dsi"; #address-cells = <1>; #size-cells = <0>;
port { dsi_in_tcon0: endpoint { remote-endpoint = <tcon0_out_dsi>; };
panel@0 { reg = <0>; }; };
Example OF graph representation of DSI host, which has ports but not has port and has child panel node.
dsi { compatible = "samsung,exynos5433-mipi-dsi"; #address-cells = <1>; #size-cells = <0>;
ports { #address-cells = <1>; #size-cells = <0>;
port@0 { reg = <0>; dsi_to_mic: endpoint { remote-endpoint = <&mic_to_dsi>; }; }; }; panel@0 { reg = <0>; };};
Example OF graph representation of DSI host, which has neither a port nor a ports but has child panel node.
dsi0 { compatible = "ste,mcde-dsi"; #address-cells = <1>; #size-cells = <0>;
panel@0 { reg = <0>; }; };
Signed-off-by: Jagan Teki jagan@amarulasolutions.com Reviewed-by: Linus Walleij linus.walleij@linaro.org
Changes for v4:
- update comments and commit message
Changes for v3:
- updated based on other usecase where 'ports' used along with child
Changes for v2:
- drop of helper
https://patchwork.kernel.org/project/dri-devel/cover/20211207054747.461029-1...
- support 'port' alone OF graph
- updated comments
- added simple code
drivers/gpu/drm/drm_of.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index 59d368ea006b..9d90cd75c457 100644 --- a/drivers/gpu/drm/drm_of.c +++ b/drivers/gpu/drm/drm_of.c @@ -249,6 +249,21 @@ 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;- }
- /*
- 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,
@@ -259,6 +274,8 @@ int drm_of_find_panel_or_bridge(const struct device_node *np, return -ENODEV;
remote = of_graph_get_remote_node(np, port, endpoint);
+of_find_panel_or_bridge: if (!remote) return -ENODEV;