Changes

* 1. First the HDMI device should be plugged in and have signal output before the Raspberry Pi is started. * 2.Please check if there is a video related file in the /dev file.* 3. Please provide us more details for us to confirm the issue.* a. First please send us your order number and tell us "Call command" "Input Device" and "Using Device".* b. What is the HDMI input device, resolution and frequency?* c. Which version of Raspberry Pi you use?* d. What is the specific calling command?* e. What is the terminal error notification?