I'm trying to use an external clock on DI0 (DI0_EXT_CLK) for parallel LCD. When I do this, I see the last line on my display flashes bright white. It is always the last line and flashes frequently without fixed timeframe. I do not see this problem when I use internal clock. Has anyone ran into this issue? Is there a way to synchronize IPU clock (HSP_CLK) and DI external clock (DI0_EXT_CLK)? Why don't I see this issue when I use internal clock? Is there something else I need to do besides setting di0_ext_clk bit in ipu_di0_general register?