Deferred Problem: Issues With Complex Dependencies Between Devices in Linux Kernel

Many devices have complex dependencies, especially on embedded platforms. They use resources provided by different devices: regulators, gpios, local buses, etc. Resource providers also use resources. …

Many devices have complex dependencies, especially on embedded platforms. They use resources provided by different devices: regulators, gpios, local buses, etc. Resource providers also use resources. Some are required, some are optional. Circular dependencies are not uncommon. The popular picture of devices as a neat tree should be replaced by an obscure jungle. Lack of proper handling of device dependencies in Linux Kernel hurts the system in multiple ways: slower bring-up of important subsystems, no support for optional resources, ugly hacks, uncoordinated development of workarounds in multiple subsystems, buggy device unbinding. Andrzej will describe current state of device dependencies in Kernel: where are the problems, how to solve it with existing frameworks, what is still missing. He will also describe his proposition to solve missing parts: Resource Tracking Framework.