On Thu, Jun 1, 2023 at 5:48 PM Hawkins, Nick <nick.hawkins@xxxxxxx> wrote: > Thank you for your valuable feedback with the solutions you have provided. > Before I proceed though I have a quick query about the fan driver. > If I were to let the user space "own" gpio pins, would it be permissible for > the userspace to feed a kernel driver data via sysfs? > > Ex: > GPIO Driver -> (OpenBMC) -> Fandriver (sysfs). > > Here the GPIO driver would provide fan presence information to OpenBMC > and then OpenBMC would provide fan presence info to the fan driver. But why? Don't be so obsessed about userspace doing stuff using sysfs, usually it is a better idea to let the kernel handle hardware. I think this is a simple thermal zone you can define in the device tree as indicated in my previous comment. > If it were permissible to provide data to the driver via this method I could > apply it to the PSU driver as well. the PSU driver which requires presence > info to verify a PSU is inserted / removed. It feels like you are looking for a way for two drivers to communicate with each other. This can be done several ways, the most straight-forward is notifiers. include/linux/notifier.h Yours, Linus Walleij
