On 11/08/2012 07:26 PM, David Gibson wrote: ... > So, let me take a stab at this from a more bottom-up approach, and see > if we meet in the middle somewhere. As I discussed in the other > thread with Daniel Mack, I can see two different operationso on the > fdt that might be useful in this context. I think of them as "graft" > - which takes one fdt and adds it as a new subtree to an existing fdt > - and "overlay" where a new fdt adds or overrides arbitrary properties > in an existing tree. Overlay is more or less what we do at the source > level in dtc already. One more thought on the differences between overlay and grafting: With overlay, it's possible to make your overlay a complete DT tree rooted at /. In some cases, you might find a lower-level node which all overlaid elements share, and root the overlay process there. With grafting, you're basically guaranteed to want the child/graft file to have different parts of itself grafted into different points in the parent/underlying tree, e.g. to add nodes to an I2C bus, an SPI bus, and perhaps some bus-less devices at the root (e.g. a new gpio-leds device). This will require that a child/graft file to consist of multiple chunks of DT all to be grafted as separate operations, whereas with overlay you may be able to get away with a single chunk to be overlaid (although with some of the use-cases discussed, even the overlay approach might require multiple chunks to be applied). -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
