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AM4378: display issue for a custom board

Part Number: AM4378

so we have a custom board and we use a 1024x600 display on this board. we were using SDK 4.03 and with the timings entered as below:

panel-timing {
clock-frequency = <33000000>;
hactive = <1024>;
vactive = <600>;
hfront-porch = <49>;
hback-porch = <49>;
hsync-len = <63>;
vback-porch = <2>;
vfront-porch = <2>;
vsync-len = <3>;
hsync-active = <0>;
vsync-active = <0>;
de-active = <1>;
pixelclk-active = <1>;
};

the panel worked fine. now we are using SDK 6.03 and the old osd057T0559-34ts is no longer listed in  and we tried using the evm one "osddisplays,osd070t1718-19ts" but that is for a 7" display and even though we have the timing for our 10.1" display it will only configure the LCD port to display as a 7" display. so i am currently in the process of finding 10.1" display panels to replace the current one in the "compatible = " field but most of them appear to not work at all (black screeen, not even backlight) or they will have backlight but no graphics.  so my questions are:

1)did the drivers get updated to "stupid-proof" the panels so only the native resolution can be displayed and if you are outside that resolution you get nothing? do i need to find a panel that has my exact resolution to work? do we need to find a new panel with more common resolutions?

2) do i need to build the kernel every time i change the dts file? i don't know if i need to or not so i have been but that takes FOREVER. when i change my dts file i build my dtb but do i need to build my kernel too? EDIT figured this out

3) is there a better way to solve this than blindly searching through the device tree options for panels that are 10.1" and trying each one separately? we are new to linux so i would like to know what the right way to solve this issue is. i tried every 10.1" display in the list and nothng worked, even the single display panel that had the same resolution as our display

  • Hello,

    The timings are no longer defined in the DT files and you need to update the following file instead: drivers/gpu/drm/panel/panel-simple.c. Here is a reference thread and the above changes were introduced in Kernel v4.19 by the mainline community.

    Regards,
    Krunal

  • so yes, that fixed it

    but that doesn't make any sense to force the dev to rebuild the kernel for this reason when you had an option to PASS IN the values before which was way more flexible. this seems more like a step back than forward. why is there not a driver that isn't specific to one panel and forces you to enter in the timing params for people who didn't design their board with the one out of eight 10.1" panels so we can use a custom one that doesn't force a kernel rebuild? i have spent days trying to figure out what is going on and how to fix it. the least YOU (meaning TI) could have done is put a comment in the evm DTS file alerting devs that we will need to make this change, where to make it, and how to make it. this was not a very user friendly change and it was not handled well at all by WHOEVER is in charge of the SDK release.