@thor Sure that it's baked into the kernel? I remember the driver made PiFM stop working but only after I started the GUI once wich used the driver. So could it be a loadable module? I think there was a config file to tweak or not load the driver at all if you needed PWM for other things. But I haven't used it for a while (Pi 3) and pretty much at noob level on Linux ;)
@fnord23 It loads a driver called snd-bcm2835 which appears to have both HDMI and PWM support in there and is partially upstreamed into the mainline kernel (staging). I'm finding the source code very hard to read. I want to know why you can't set short buffer sizes. It's a PWM controlled by a DMA. There should be no lower limit to how short that buffer is, but in practice, it looks like an artificial limit of 10 ms is enforced.
