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HDMI setting

Dan Liu
Prodigy 175 points


Hi,
On platform OMAP4430, how to modify the HDMI output setting?
Below is the relative setting on our board.

shell@android:/sys/devices/omapdss/display1 # cat timings
74250,1920/88/148/44,1080/4/36/5

shell@android:/sys/devices/platform/omapdss/overlay0 # cat global_alpha       
255
shell@android:/sys/devices/platform/omapdss/overlay0 # cat input_size         
1280,800
shell@android:/sys/devices/platform/omapdss/overlay0 # cat position           
0,0
shell@android:/sys/devices/platform/omapdss/overlay0 # cat output_size        
1280,800
shell@android:/sys/devices/platform/omapdss/overlay0 # cat x_decim            
1..255
shell@android:/sys/devices/platform/omapdss/overlay0 # cat y_decim            
1..255
shell@android:/sys/devices/platform/omapdss/overlay0 # cat screen_width       
0
shell@android:/sys/devices/platform/omapdss/overlay0 # cat zorder
0
shell@android:/sys/devices/platform/omapdss/overlay0 # cat pre_mult_alpha     
1

1. Form TV we can tell the HDMI output resolution is 1920*1080, this is only matched with "timings" setting in display1. Can you tell the mean of each paramter in "74250,1920/88/148/44,1080/4/36/5"?
2. The bootup image is only shown on the left top of TV. I think the default resolution is 640*480, right? How can I set it to other resolution or how to set it to show in the middle?
3. Every time to show UI to TV, we need to type in several commands as below:
echo "1" > /sys/devices/platform/omapdss/display1/enabled
echo "0" > /sys/devices/platform/omapdss/overlay0/enabled
echo "tv" > /sys/devices/platform/omapdss/overlay0/manager
echo "1" > /sys/devices/platform/omapdss/overlay0/enabled
But once the system is rebooted, we need to set it again.
Together with both above two settings, can we set it permanently?
The default u-boot environments setting as below:
OMAP44XX SDP # printenv
bootargs=console=ttyO2,115200n8 mem=456M@0x80000000 mem=512M@0xA0000000 init=/init vram=10M omapfb.vram=0:4M androidboot.console=ttyO2
bootdelay=3
baudrate=115200
ipaddr=128.247.77.90
serverip=128.247.77.158
netmask=255.255.254.0
bootfile="uImage"
stdin=serial
stdout=serial
stderr=serial
bootcmd=booti mmc0
ethact=KS8851SNL

Environment size: 325/131068 bytes


Best Regards,
Dan

  • 0
    TI__Expert 4120 points

    Hi Dan,

    First of all, which software release and hardware platform you are using? By default on ICS releases with Blaze Tablet 2 Platform, cloning feature is enabled so that the UI content gets cloned on to TV automatically wherein the HDMI timings is chosen by HWC layer to match the aspect ratio of UI content resolution.

    HDMI Timings Parameters denote the following parameters.

    "pixel_clock,x_res/hfp/hbp/hsw,y_res/vfp/vbp/vsw"
    • Following are the descriptions for the above parameters and more description can be found at http://www.epanorama.net/documents/vga2rgb/terms.html
      • Height and Width of the resolution.
      • Pixel clock required to support that resolution.
      • Timing parameters
        • Horizontal front porch, hfp
        • Horizontal Sync Width, hsw.
        • Horizontal back porch, hbp.
        • Vertical Front porch, vfp.
        • Vertical Sync Width, vsw.
        • Vertical back porch, vbp

    You can refer to the following web page for further details on how to set the HDMI timings using sysfs command.

    http://omappedia.org/wiki/Bootargs_for_enabling_display#How_to_read_and_set_EDID_timings_for_HDMI

    Thanks & Best Regards,

    Venkat