the image is segmented which screen is hdmi-output

hello,
Tx1 connect two screen,one is hdmi-output with 1920x1080p@60Hz and another is dsi-output with 720x576@50Hz. Then I use openGL to display,but the image is segmented which screen is hdmi-output.
But the image is not be segmented when hdmi-output only. I’m very confused about how to make hdmi-output display normally at the same time dsi-output display.

I would be very grateful for any suggestion.