o You'll most likely have to figure out how to toggle power to the dGPU. This is mainboard specific, can be a GPIO, for instance. So I suggest to boot with the vendor firmware, dump GPIOs, toggle the dGPU, and dump again. With some luck you'll find a GPIO that changes respec- tively. You can find an example of similar code in src/drivers/lenovo/ hybrid_graphics/.
I'll work on this, then.
A couple of GPIOs do change when the dGPU is enabled or disabled. But why would any additional code need to be written? I thought that the point of passing gpio.h to ramstage was that it resolved these issues, allowing us to do what vendor firmware does where it counts, without understanding/parsing individual values.
Of course, I haven't tried another image yet so the above could be true, and therefore, irrelevant, but I wouldn't know it.