On 07/06/2023 08:26, Billy Tsai wrote: > >> > >> He felt what he was trying to accomplish met the documented > >> expectations. Are there some changes that need to be done in mfd.txt to > >> further clarify when to use it and when not to? > > > I think mfd.txt clearly states: > > "For more complex devices, when the nexus driver has to > > probe registers to figure out what child devices exist etc, this should > > not be used. In the latter case the child devices will be determined by > > the operating system." > > About the mfd: > For our pwm and tach devices, there is no need to check/apply any hardware register from parent to determine child’s existence or functional. > They don’t have any dependency on the parent node. In fact, it doesn’t require a specific driver to bind with the "aspeed,ast2600-pwm-tach" label. Their purpose is solely to share the same clock, reset phandle and base address. The main reason for using simple-mfd in this case is because these two independent devices share the same base address. Actually one more thoughts. I have doubt that you have two independent devices. If you share the clock, reset line and register address space, this means *you do not have two independent devices*. You have most likely only one device. Best regards, Krzysztof
