Debug Display

Follow the steps below to debug the display functions for your JH7110.
  1. Follow the steps in Test Case Configuration to configure the test environment.
    Note: Make sure you have configured libdrm and modetest before compiling and burning an image.
  2. After you have completed the kernel start-up, use the following command to verify the display functions and connection status. 
    modetest -M starfive
    The following legends and tables display an example output and descriptions.
    • Debug output 1:
      Figure 1. Debug Display 1
      Table 1. Debug Display 1
      Legend Label Description
      ① possible crtcs Available Cathode Ray Tube Controller (CRTC) devices
      ② status Whether the display connector is connected or not
      ③ name The name (type) of the display connector
      ④ encoders The connected encoders
      ⑤ modes The supported display modes
      ⑥ value The Extended Display Identification Data (EDID) of the screen
    • Debug output 2:
      Figure 2. Debug Display 2
      Table 2. Debug Display 2
      Legend Label Description
      ① id The CRTC 0x00000001 mentioned in row ① of table Debug Display 1, which means the CRTC is available for use.
      ② id The CRTC 0x00000002 mentioned in row ① of table Debug Display 1, which means the CRTC is available for use.
      Note: If the displayed CRTC is 0x00000003, both of the CRTCs are available for use.
    • Debug output 3:
      Figure 3. Debug Display 3
      Table 3. Debug Display 3
      Legend Description
      ① The CRTC and its connected plane