Re: MXSFB error: -ENODEV: Cannot connect bridge

Roland Hieber
2024-02-12T11:07:46Z

On Thu, Feb 08, 2024 at 12:58:02PM -0300, Hiago De Franco wrote:
> Hello all,
>
> while doing some tests with kernel v6.8-rc3 and Colibri iMX7D, we
> noticed the following error:
>
> [ 0.432547] mxsfb 30730000.lcdif: error -ENODEV: Cannot connect bridge
>
> This was introduced by commit edbbae7fba495284f72f05768696572691231558
> ("ARM: dts: imx7: add MIPI-DSI support"). This patch is routing the
> lcdif to the mipi_dsi_in_lcdif endpoint, however we do not have the DSI
> pins available in our edge connector. Instead, we use the parallel RGB
> LCD interface directly with, as example, an external LVDS transmitter:
>
> &lcdif {
> ...
> status = "disabled";
>
> port {
> lcdif_out: endpoint {
> remote-endpoint = <&lcd_panel_in>;
> };
> };
> };
>
> By applying the following patch, the issue is gone and the LVDS works
> again:
>
> diff --git a/arch/arm/boot/dts/nxp/imx/imx7s.dtsi b/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
> index ebf7befcc11e..9c81c6baa2d3 100644
> --- a/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
> +++ b/arch/arm/boot/dts/nxp/imx/imx7s.dtsi
> @@ -834,16 +834,6 @@ lcdif: lcdif@30730000 {
> <&clks IMX7D_LCDIF_PIXEL_ROOT_CLK>;
> clock-names = "pix", "axi";
> status = "disabled";
> -
> - port {
> - #address-cells = <1>;
> - #size-cells = <0>;
> -
> - lcdif_out_mipi_dsi: endpoint@0 {
> - reg = <0>;
> - remote-endpoint = <&mipi_dsi_in_lcdif>;
> - };
> - };
> };
>
> mipi_csi: mipi-csi@30750000 {
> @@ -895,22 +885,6 @@ mipi_dsi: dsi@30760000 {
> samsung,esc-clock-frequency = <20000000>;
> samsung,pll-clock-frequency = <24000000>;
> status = "disabled";
> -
> - ports {
> - #address-cells = <1>;
> - #size-cells = <0>;
> -
> - port@0 {
> - reg = <0>;
> - #address-cells = <1>;
> - #size-cells = <0>;
> -
> - mipi_dsi_in_lcdif: endpoint@0 {
> - reg = <0>;
> - remote-endpoint = <&lcdif_out_mipi_dsi>;
> - };
> - };
> - };
> };
> };
>
> I would like to know your opinion about this patch before sending it,
> does it makes sense for you? I understand that routing to endpoint
> should be done in the SoM device tree, so we are free to rout other
> endpoint without issues.

As far as I understood, the LCDIF -> DSI connection is always present in
the SoC. Can you overwrite the routing in your dts like this:?

&lcdif_out_mipi_dsi {
remote-endpoint = <&lcd_panel_in>;
};

I'm not sure what is the best default solution here for imx7s.dtsi. Also
the labels don't work out in that case, this could be improved.

Regards,

- Roland

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