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AM3874 base board LCD issue

Alyautdin Roman
Intellectual 345 points
Other Parts Discussed in Thread: AM3874

Hi,

I am using custom board based on AM3874 and face an issue with LCD monitor output.

for tuning the vpss parameters following script is used:

    modprobe vpss sbufaddr=0xA0200000 mode=hdmi:1024x768@60,dvo2:1024x768@60
    sleep 1
    modprobe ti81xxfb vram=0:24M,1:16M,2:6M
    sleep 1

    echo 0 > /sys/devices/platform/vpss/display0/enabled
    echo 0 > /sys/devices/platform/vpss/display1/enabled

    echo 68250,1280/167/79/10,768/10/23/10,1 > /sys/devices/platform/vpss/display0/timings
    echo 68250,1280/167/79/10,768/10/23/10,1 > /sys/devices/platform/vpss/display1/timings
    echo triplediscrete,rgb888 > /sys/devices/platform/vpss/display1/output


    echo 5 > /sys/devices/platform/vpss/system/tiedvencs


    echo 1 > /sys/devices/platform/vpss/display0/enabled
    echo 1 > /sys/devices/platform/vpss/display1/enabled
    echo 2:hdmi,dvo2 > /sys/devices/platform/vpss/graphics0/nodes

    fbset -xres 1280 -yres 768 -vxres 1280 -vyres 768


As the result e picture on HDMI is ok, but the picture on the LCD screen is shifted
(likewise cyclic buffer). Moreover sometimes the picture shakes.
None problems are seen on hdmi.

Could you suggest any ideas regarding the problem.
I think this is smth with the timings?!

The output "picture" is Xorg + LightDM.
PSP TI81XX-LINUX-PSP-04.04.00.01.tgz

  • 0 in reply to Margarita Gashova
    Intellectual 345 points

    Hello Margarita,

    Thanks for the answer.

    The provided link is for PSP_04.01.00.02.
    We use vpss from PSP-04.04.00.01,
    but I have the VPSS doc from the package.


    I did some investigations and found that if I use
    only LCD  (without HDMI) with the same timings - everything is ok.

        echo "Configuring fb0 to LCD"
        echo 1:dvo2 > /sys/devices/platform/vpss/graphics0/nodes
        echo 0 > /sys/devices/platform/vpss/display1/enabled
        echo 68250,1280/167/79/10,768/10/23/10,1 > /sys/devices/platform/vpss/display1/timings
        echo triplediscrete,rgb888 > /sys/devices/platform/vpss/display1/output
        echo 1 > /sys/devices/platform/vpss/display1/enabled
        fbset -xres 1280 -yres 768 -vxres 1280 -vyres 768

    So maybe you could tell m how to enable HDMI in parallel.
    The upper code allows to do so but it brakes image on the LVDS screen.
    Maybe I did the dual display outout in a wrong maner,
    so could you recommend me anything.

    My aim is to have both screens working

    Thanks in advance,
    Roman

  • 0 in reply to Alyautdin Roman
    TI__Guru* 80190 points

    Hello,

    Alyautdin Roman said:
    The provided link is for PSP_04.01.00.02.
    We use vpss from PSP-04.04.00.01,
    but I have the VPSS doc from the package.

    Check in the VPSS doc from the package chapter:

    Cloning fb0(graphics0) output to both HDMI VENC and DVO2 VENC

    Best Regards,

    Margarita