i got some more progress, i got the lvds panel and backlight working with u-boot, i also switched to u-boot 2021.07-rc3-dirty, i have an mmc driver enabled but so far it wasnt able to detect any sdcards that i plugged in maybe the pin configs are wrong, i still havent tried configuring nand , i migrated my build enviroment to a fresh install of debian 10 on a vm and my build errors that i have encountered are gone so far. heres an image of the working lvds panel : https://drive.google.com/file/d/19-p3G8RATX2tDcESXd6cOlq55flDeED4/view?usp=sharing
Koray Bilir <koray...@gmail.com>, 25 May 2021 Sal, 14:29 tarihinde şunu yazdı: > hello to the u-boot community, last week i wanted to do some hardware > hacking and came across one of my nameless chinese brand sun7i a20 tablets > poked around in adb shell, mounted the NANDA partition and to my surprise > it was running u-boot v2011 , so i wanted to put a linux kernel on there to > see if it would boot > unfortunately the u-boot was outdated and couldn't boot it, tl dr; i am > trying to write a device tree file so i can successfully port U-BOOT > v2021.07-rc2-00238-geb53b943be-dirty. > So far I have "successfully" compiled a u-boot.bin although binman gives > an error of "cant find u-boot.dtb" the u-boot.bin works fine on the device. > Sorry for my rambling. I just wanna give the most information in one post. > so far I was able to write a simple .dts file for my board to get the > debug uart ports working. luckily I discovered some test points on the > board that were for uart tx rx. > I got the uart interface working. I don't have an ftdi at the moment so > i'm using an arduino as an usb to serial passthrough long story short i was > able to get the u boot shell working > and I was able to interface with the device. since its my first time cross > compiling, u-boot and also device tree files i need some guidance to where > should i look, one question that i have is > Is there any pre-made building environments that I can just run on a > virtual machine, im currently using my laptop which has debian 10 on it to > compile and i'm not sure if I did everything right to get my build > environment working. I have access to the stock rom of my device so i cant > brick it and also i have access to the source code of the u-boot 2011 > version that was on the board from > the factory. unfortunately this device has android 4.2.2 installed on it > and i couldn't find any device tree files on it, i have the sysconfig.fex > file that has the pinouts and config data on it > So basically I'm trying to convert the sysconfig.fex to a dts file. > > my objectives right now are: > setup ram correctly > get nand working > get sd/mmc working > get usb working > get 24bit lvds panel working > get touchscreen working > get audio working > and finally get some sensors working that the board has > > I'm having no luck getting the nand and lvds panel working. I haven't > tried sd/mmc , audio and touchscreen but i had usb working with some > settings, i disabled it when i was debugging for other stuff. > This gt90x v4 board is found in many nameless chinese tablets so I'm > hoping this little project of mine can help others. > also i see an unpopulated place that could take another nand chip , i'll > have to try to see if it would work > if any of you are interested in this or want to look at everything i got i > can for the u-boot repository and commit my changes there and if any of you > want to help you are more than welcome since > this is my first time doing embedded stuff im learning as i go along so > feel free to correct me. > I can provide the source code of the 2011 u-boot that had everything > working on the device and I can provide everything I have mentioned earlier > (file wise). > > Let's get to the board details. > > ALLWINNER A20 SUN7I DUAL CORE CPU > 2x NANYA MTT 256X16DDR3 V 1330 RAM CHIPS (device supposedly has 1gb of ram) > TOSHIBA JP5415 TAIWAN 13359 A E / TC58TEG6DCJTA00 (8GB NAND) > AXP209 0448CB 66K1 > GSL3680 64A0D4281N > REALTEK RTL8188ETV D700331 GD27 > E203460 9INCH 1024X600 24BIT LVDS PANEL > > Thats all of the major components on the board that i can see, i'll have > an image of the board down below. > > https://drive.google.com/drive/folders/17zZTsgPHKktV4VARHAxR8tpHS4P04U7x?usp=sharing > > I would be super happy if anyone is able to point me in the right > direction or help me. > > -Koray >
