imx8m Nano shows no display with monitor or hdmi display

[arsalanraghib]

I have an i.MX 8M Nano board. I want to attach a 5.5 inch WaveShare Screen 1920x1080 display panel as an output display but i cannot see anything except the initial charaters of NXP (in very dispersed order) and then screen appears black. When i connect the screen's touch interface with USB C port of Nano board. It continously output the following lines after every 4 or 5 seconds on COM port.  

And when i connect the display after it boots up it shows the following lines but still nothing appears.

I have also tried without the touch interface but nothing seems to work. Moreover i have a DVI monitor and when i connect hdmi to dvi connector the monitor also shows nothing. I also tried to change the screen resolution according to monitor display ( video=HDMI-A-1:1280x1024-24@60) but still no success. 

I am running "android_p9.0.0_2.3.1_image_8mnevk" image. Since i am new to this board please any help would be highly appreciated. 

[jimmychan]

Are you using i.MX8MN EVK?

If yes, please download the demo image and the documentation from here:

https://www.nxp.com/design/software/embedded-software/i-mx-software/android-os-for-i-mx-applications...

In the documentation, there is Android_Quick_Start_Guide.pdf. You can follow the Quick Start Guide to play the board with demo image first.

And then follow the Android_User's_Guide.pdf to build the Android BSP images.

[arsalanraghib]

Not yet. I have booted the new image. The display is correct on 1920x1080 hdmi monitors. But still no display on the 5.5 inch screen or DVI monitors. 

[jimmychan]

Hello,

You may need to add the following patch for support the DVI mode.

--- a/drivers/gpu/drm/imx/hdp/imx-hdmi.c
+++ b/drivers/gpu/drm/imx/hdp/imx-hdmi.c
@@ -221,6 +221,15 @@ static int hdmi_scdc_tmds_config(struct imx_hdp *hdp)
hdp->hdmi_type = HDMI_TX_MODE_HDMI_1_4;
}

+ if (hdp->connector.display_info.cea_rev == 0) {
+ /* If the CEA/CTA revision is zero, it means no cea/cta
+ * extention blocks were found. So no HDMI vendor specific
+ * descriptor is present. So we use DVI mode.
+ */
+ pr_info("DVI mode detected\n");
+ hdp->hdmi_type = HDMI_TX_MODE_DVI;
+ }
+
data_in.buff = &buff;
data_in.len = 1;
data_in.slave = 0x54;
--

Best regards,

Jimmy