ADV7511 on Zed board, 800x480 TFT supports?

Hi, 

I am using Zed board linux reference design.

my plan is to drive TFT 800x480, so I used HDMI to TFT decoder driver chip (TFP401A)

basically the TFT timing is same with 800x600 except for 120 lines,

same pixel clock, and etc.. only vertical blank differs

so when I choose the resolution 800x600, it successfully displayed on 800x480 TFT with the bottom 120 lines clipped.

but some problems with application development and with the touch screen position.

Y coordinate of touched position is not translated correctly, because the linux think it's resolution is 800x600, not 800x480.

so I want to know there is any way to enable 800x480 resolution?

is possible to enable 800x480 resolution with the modesetting  with EDID is disabled?

Many thanks in advance

Kim