Before learning embedded Linux, you must have a C language foundation. It doesn't matter whether there is an assembly basis or not (just a few assembly instructions can be used at a glance). To what extent should C language be learned? Of course, the more familiar, the better. If you are not familiar with it, you should also have basic skills. For example, write an array to sort, sum the input numbers and so on. The only way to learn C language is to write more programs and practice more. It doesn't matter if there is a compilation error, you can solve it yourself. It doesn't matter if the execution is wrong, analyze it yourself. I used to practice C language with VC, and often tried to write some C language contest topics. They are all pure C, pure mathematics and pure logic topics, and do not involve interfaces. The embedded video of Maker College is very suitable for improving your programming ability.