Valve Corporation Embedded Software Engineer interview questions

Applied online, heard back relatively quickly. Had lunch with recruiter/hiring manager, they decided to move forward with an interview loop. Brushed up on embedded questions (bit manipulation, string/array management, kernel optimization, multithreading, interrupt contexts) and just in case, also brushed up on irrelevant high level CS BS, such as graphs, binary trees, heaps, etc. Unfortunately, they only asked game development-related software questions (geometry-heavy simple math questions implemented efficiently in code), and then proceeded to assume that kernel software engineers should know how to design hardware at a high level of competency. Explained that I could design simple hardware like a prototype gamepad or customize a reference design, but it takes years of relevant experience to make something ready for mass production. They ended the interview loop early since I didn't do well on the software question, did not offer me a chance to redeem myself with another question. I went home with a bad taste in my mouth both about their level of professionalism and their hardware design prospects. They have a cavalier attitude about hardware mass production and driver development which is going to serve them very poorly as they attempt to ramp up. Most of the real work in designing a hardware product comes after the prototype phase, as Kickstarter has publicly demonstrated.