On Mon, Sep 12, 2016 at 02:29:37PM +0200, Sebastian Frias wrote: > My question is about submitting DT properties/nodes (describing some HW) for > which there is no Linux driver. Like register addresses for HW blocks, > including HW capabilities of said HW blocks, which may or may not be setup > by Linux directly. > > The idea being that since DT describes the HW and is usually shared with the > bootloader (yet stored in the Linux kernel tree), all layers of the stack > could use the same DT and each layer would use relevant properties. So the > DT would describe the whole SoC even if not all HW blocks have a Linux > driver. > > 3rd party users of said SoC could then write kernel modules for such HW > blocks using the DT description. The DT would thus become the authoritative > source of information regarding register programming for the SoC. I don't follow this part entirely. Why are you expecting thrid parties to write a driver for those blocks rather than upstreaming a driver for them? > Currently, HW blocks for which there is no public driver (that it is > accessed through user-mode libraries or firmware) require a separate > HW description (be it Documentation, headers, etc.) > > Since the DT describes the HW, it would make sense to expose the HW through > DT, that would centralise the HW description. I would generally agree that the hardware should be described in DT. The difficulty is that without a 'real' user it's not always possible to tell if we're describing the thing correctly. Putting smoething together that's only sufficient to support some out-of-tree driver with implicit assumptions that we are not aware of is far from fantastic. > However, after discussing over IRC, it looks like there was no guidance on > this. Some people think submitting DT properties/nodes without a corresponding > Linux driver is frowned upon, while others thought it was an odd limitation > and suggested asking here. Unfortunately, I think that the area is sufficiently vague that there simply is no clear and general answer. For the sake of discussion, an example of a particular block, along with what you expect/need to describe would be helpful. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html