Re: [PATCH v12 00/18] drm: Add Samsung MIPI DSIM bridge

Rasmus Villemoes
2023-02-17T18:23:51Z

On 07/02/2023 10.09, Rasmus Villemoes wrote:

> I managed to get the whole chain lcdif -> mipi -> bridge -> dp-connector
> to probe with these settings
>
[...]
> Now hotplug-detect doesn't work with the current sn65dsi86 driver, but
> that's a separate issue; when I boot with a monitor attached, its edid
> is correctly read out. But I still don't get any output, and the monitor
> says "no signal" - my naive attempt (which has worked fine in other
> cases) was to just dd /dev/urandom to /dev/fb0, so I'm clearly missing
> some important step.

No idea if it's important, but in the NXP kernel, there's a

display-subsystem {
compatible = "fsl,imx-display-subsystem";
ports = <&lcdif1_disp>,
<&lcdif2_disp>,
<&lcdif3_disp>;
};

node in imx8mp.dtsi, and when commenting out that node, the graphics
ceases to work, even if all the devices in the lcdif->mipi->bridge chain
actually probes. However, adding a corresponding node in mainline, which
does have a driver for that "fsl,imx-display-subsystem", makes no
difference; with or without that, I do get a /dev/fb0 device and the
whole chain probes, but again the monitor says no signal.

Rasmus