IMX8MQ setup HDMI issues

claire_chen — Thu, 17 Jun 2021 05:43:40 GMT

Dear All，

We now have a custom screen (800x600), which needs to be equipped with a screen. However, according to the IMX8MQ manual and driver code, the IMX8MQ does not support 800x600 mode. We refer to the method of NXP forum：https://community.nxp.com/t5/i-MX-Graphics/Driving-a-1080x1920-portrait-HDMI-screen/m-p/1218253#M92
Customized screen parameters are as follows:
               clock-frequency = <40000000>;
                hactive = <800>;
                vactive = <600>;
                hfront-porch = <40>;
                hback-porch = <100>;
                hsync-len = <10>;
                vback-porch = <30>;
                vfront-porch = <3>;
                vsync-len = <2>;

So I'm   adding the following code on driver source file（drivers/gpu/drm/imx/hdp/imx-hdp.c).
       { DRM_MODE("800x600", DRM_MODE_TYPE_DRIVER, 40000, 800, 840,
                   850, 950, 0, 600, 603, 605, 635, 0,
                   DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),
          .vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

And the driver source file (drivers/gpu/drm/imx/hdp/t28hpc_hdmitx_table.c) was commented out in 40 m pixel clock is set to open,Then connect to the screen, boot kernel has printed information:

[    1.436958] [drm] Pixel clock frequency: 40000 KHz, character clock frequency: 40000, color depth is 8-bit.
[    1.436972] [drm] Pixel clock frequency (40000 KHz) is supported in this color depth (8-bit). Settings found in row 31
[    1.437013] [drm] VCO frequency is 3202200
[    1.437021] [drm] VCO frequency (3202200 KHz) is supported. Settings found in row 16

The HDMI screen still shows NO SIGNAL when the driver has found a 40M pixel clock.

claire

topic IMX8MQ setup HDMI issues in i.MX Processors

IMX8MQ setup HDMI issues