Panel timing configuration with i.MX 93

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Panel timing configuration with i.MX 93

1,150 Views
spawn
Contributor III

Hello,

I'm trying to add a parallel panel to the device tree for a board with i.MX 93. So far I can display stuff on the panel but the horizontal lines of pixels are not perfectly aligned vertically (some are shifted a few pixels to the left).

Here is the datasheet.

The panel has PCLOCK, DE and 18xRGB lines. I figured I the timings may be wrong, but I tried many configuration without success.

Here is the device tree node I'm currently using (linux kernel v6.1.55) :

	panel {
		compatible = "panel-dpi";
		power-supply = <&reg_vdd_3v3>;
		backlight = <&backlight>;

		panel-timing {
			clock-frequency = <33260000>;
			hactive = <800>;
			vactive = <480>;
			hfront-porch = <12>;
			hback-porch = <12>;
			hsync-len = <256>;
			vfront-porch = <12>;
			vback-porch = <12>;
			vsync-len = <45>;

			de-active = <1>;
			pixelclk-active = <1>;
		};

		port {
			panel_in: endpoint {
				remote-endpoint = <&display_out>;
			};
		};
	};

Maybe someone knows what I'm doing wrong ?

Thank you.

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1,095 Views
spawn
Contributor III

So, it looks like that when pixels are set (such as when text is written), the wrong pixels are set as if there IS somerhing wrong related to the bits_per_pixel or bit_depth or somerhing similar. Maybe some buffer (in the chip itself ?) has 15 or 16 bits per pixel by default and is not configured to have 24 bits per pixel when I set rgb888 in the device tree ?

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1,110 Views
spawn
Contributor III

I reopened the topic, since its appears that the horizontal lines are shifted left when fsl,interface-pix-fmt is set to "rgb888" in the &parallel_disp_fmt node. When fsl,interface-pix-fmt is set to "rgb666", the horizontal lines are barely shifted left. There may be a bug in the I.MX drm or lcdifv3 driver, or I may have misconfigured something.

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1,127 Views
spawn
Contributor III

Never mind. The problem is not related to the device tree at all, but to text rendering somehow. This thread can be closed.

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