Hi Grant, Am 14.05.2014 12:08, schrieb Grant Likely: > More generally I am concerned about whether or not overlays > will introduce corner cases that can never be handled correctly, > particularly in how multiple overlays will get handled. I want to see > very clear rules on what happens when multiple overlays are applied, and > then removed again. Is it possible to remove overlays out of order? If > so, what are the conditions that would not be allowed? Yes, it is possible that an overlay depends on another. The problem is not, that an overlay is removed other overlays depend on, but that nodes of an overlay may depend on the to-be-removed overlay and the resulting devicetree can become inconsistent. I have an SPI Bus with two slaves. The second slave is used only on one of our boards. That is why we split the overlays the following way: xxxx_spi1.dts: Pinmux for SPI-Bus and activation of spi-controller. Pinmux for CS0 and definition of first slave. xxxx_spi1_cs1: Pinmux for CS1 and definition of second slave. When the overlay for the bus is removed, the overlays for the second slave does not make any sense anymore. It is even worse in a scenario we have with a test board. One of the slaves is an spi-io-controller with a few bitbanging i2c masters. In an extreme case, each component is defined in a separate overlay and only the overlay with the master is removed. I know, that this is completely sick. The devices are removed cleanly because of the device dependency. Michael -- 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
