Hi Clemens, On Fri, Jan 29, 2021 at 4:24 PM Sven Van Asbroeck <thesve...@gmail.com> wrote: > > LEN_ON = 409, LED_OFF = 1228 and > LED_ON = 419, LED_OFF = 1238 > produce the same result. you can't see the difference between the two > when scoping the channel. there are probably more ways to do this, > some might surprise us. It's a tricky chip.
Please ignore this example, it's bogus. In my defence, it's a Friday afternoon here :) But consider the following: imagine the bootloader has enabled a few pwm channels, and the driver's .probe() has left them on/unchanged. Then the user enables another pwm channel, and tries to change the period/prescaler. How would pca9685_may_change_prescaler() know if changing the prescaler is allowed? And the following: imagine the bootloader has enabled a few pwm channels, and the driver's .probe() has left them on/unchanged. After .probe(), the runtime_pm will immediately put the chip to sleep, because it's unaware that some channels are alive. I'm sure I'm overlooking a few complications here. probe not changing the existing configuration, will add a lot of complexity to the driver. I'm not saying this is necessarily bad, just a tradeoff. Or, a management decision. Sven
