I have managed for a while now to build openwrt for my device (DIR-853-A3). It is working well thanks to the work done by others.
Since the last few commits done on the master tree now to add the device to the official openwrt it is basically just a DTS plus another additions to 3 files.
My issue is that the device cannot be flashed without accessing the console. and to do that it needs to be open and have 3 pins soldered. The reset button option found in other devices does not work.
My question is: Will the openwrt maintainers accept such device to be added to the list?
I did manage to flash from the factory image though. This is using a binary called imgcrypt that I found in the official dlink sources. I guess they left it by mistake as it is only available in a single version of the source code.
I think that should not be an issue as long as it's clearly documented in your commit message. There's multiple devices (commit 0c24b363a6 e.g.) that require UART access and have been added.
As for the D-link binary you need, no idea how to go about it. You can ask on the mailing list when you send in your patch maybe?
Thanks again @Borromini, as usual you very helpful.
I will have a look at the commit.
In fact there are 2 parts for this. The first one is that the dlink source code for my device (and all the new dlink ones with mt7621) use a modified mkimage and the source code is available from dlink. Instead of padding the uboot with 00 like in openwrt it actually appends other details like the model number and version etc. This is used by the stock firmware to check that it is flashing the correct version.
This is a hexdump of the stock image decrypted and openwrt
The second part is the imgcrypt is a 32bit binary and no source code is availble for it (at least in all versions of dir-853, 1360, 878...etc.
I am not sure how to go about it or if its even worth the change just to move from factory to openwrt. I am also not the best suitble candidate for the task I will leave the details here in case someone needs them.