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@xxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> 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-jagan@xxxxxxxxxxxxxxxxxxxx/
> - 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;
>
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
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