On Fri, 22 Dec 2017 13:44:27 +0100 Johan Hovold <johan@xxxxxxxxxx> wrote: [...] > I'd suggest reiterating the problem you're trying to solve and > enumerating the previously discussed potential solutions in order to > find a proper abstraction level for this (before getting lost in > implementation details). > The main point here is in short words: Having a device powered on or off when the uart it is attached to, is used or not used anymore, so the already available userspace applications do not need to be changed. I digged out a bit around: alternative aproaches were: adding hooks to the uart/tty layer: https://marc.info/?l=linux-kernel&m=143333222014616&w=2 https://marc.info/?l=devicetree&m=143130955414580&w=2 I do not find it right now in my archive: adding a virtual gpio for dtr to the omap_serial driver. The driver behind the virtual io would then handle pm. One reason it was rejected was that the devicetree should only contain real hardware and not virtual stuff. Regards, Andreas
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