How to config HDMI output to 1280x720@30fps?

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How to config HDMI output to 1280x720@30fps?

Contributor I

Dear NXP,

     On I.MX6Q reference code, the HDMI output is 1920x1080@60fps or 1280x720@60fps,  but we want to support 1280x720@30fps output, I did some changes as below:

     1. u-boot parameter:

           Kernel command line: console=ttymxc0,115200 video=mxcfb0:dev=hdmi,1280x720M@30,if=RGB24,bpp=32 

     2. kernel:

             2.1  add new_mode for 1280x720@30fps output,

              static const struct fb_videomode new_mode = {
                      NULL, 30, 1280, 720, 26936, 220, 110, 20, 5, 40, 5,
                      FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT,
                      FB_VMODE_NONINTERLACED | FB_VMODE_ASPECT_16_9, 0

             2.2  add new_mode in function mxc_hdmi_edid_rebuild_modelist() 

               fb_add_videomode(&new_mode, &hdmi->fbi->modelist);

     3. enable function dump_fb_videomode()

     4. kernel log:


mxc_hdmi 20e0000.hdmi_video: Detected HDMI controller 0x13:0xa:0xa0:0xc1
fbcvt: Refresh rate not CVT standard
fbcvt: 1280x720@30: CVT Name - Not a CVT standard - 0.921 Mega Pixel Image
fb_videomode = 29 1280 720 28368 160 32 3 8 128 5 2 0 32
       1. Why the fb_videomode is different with new_mode?
       2. Why I can't find the parameters of fb_videomode in the code?
       3. Why the HDMI display is still 60fps?
       4. How to change the code to support 1280x720@30fps?
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NXP TechSupport
NXP TechSupport

did you set your new mode  according to "VESA and Industry Standards and Guidelines for Computer Display Monitor Timing (DMT)" specification? how did you set it?

pls refer to the discussion as below. hope helpful for you 

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