Device Tree for Picasso seems broken

I don't know if it's my mess-up, but I was not able to build the exact same dtb image as found in the official boot.img. My built dtb image is 4.4M when concatenated while the official one is only ~800K, and most importantly, when packaged into boot.img, the one built by me does not work and fails straight into bootloader. In console-ramoops I can't even see kernel messages during such a crash, which probably means the kernel isn't even booted enough to output anything to ramoops. I tried to unpack the concatenated dtb images and compare them one-by-one, but it seemed to me that even the same dtb in the two images do not really match up and differs quite significantly.

In my current effort to port LineageOS 17.1 to this device, I resorted to using OSS kernel + prebuilt DTB / DTBO for now. I hope that this can be sorted out soon as some of my kernel changes had to be dirty hacks without functional OSS DTB / DTBO.

Of course, since I'm not aware of anyone else that is currently trying to build kernel + dt for this device, it could be totally my fault instead of Xiaomi's. But for now since I do not know, I'm keeping this open until someone fixed it or could help figure out why mine does not work. My forked kernel source code (with dt included) is at https://github.com/PeterCxy/android_kernel_xiaomi_sm7250

从 issue 中链接的 fork 内核源代码和 device-tree 文件开始，然后将其拼接后的 DTB 输出与官方 boot.img 以及预构建的 DTB/DTBO 进行比较。检查打包差异以及启动期间的 ramoops 输出。完成的标准是确定原因，并生成一个能够打包进 boot.img 且可以成功启动 Picasso 的 DTB/DTBO。