Hi Grant, On Mon, Jun 13, 2011 at 07:32:15AM -0600, Grant Likely wrote: [...] > +Linux board support code calls of_platform_populate(NULL, NULL, NULL) > +to kick of discovery of devices at the root of the tree. The > +parameters are all NULL because when starting from the root of the > +tree, there is no need to provide a starting node (the first NULL), a > +parent struct device (the last NULL), and we're not using a match > +table (yet). For a board that only needs to register devices, > +.init_machine() can be completely empty except for the > +of_platform_populate() call. > + > +In the Tegra example, this accounts for the /soc and /sound nodes, but > +what about the children of the soc node? Shouldn't they be registered > +as platform devices too? For Linux DT support, the generic behaviour > +is for child devices to be registered by the parent's device driver at > +driver .probe() time. So, an i2c bus device driver will register a > +i2c_client for each child node, an spi bus driver will register > +it's spi_device children, and similarly for other bus_types. > +According to that model, a driver could be written that binds to the > +soc node and simply registers platform_devices for each of it's > +children. The board support code would allocate and register an soc > +device, an soc device driver would bind to the soc device, and > +register platform_devices for /soc/interrupt-controller, /soc/serial, > +/soc/i2s, and /soc/i2c in it's .probe() hook. Easy, right? Although I do not quite understand what the "soc device driver" is here. Looking at the devicetree/test code, I do not find this driver and its .probe() hook. Instead, of_platform_bus_create will create platform_device for the provided device_node, and also recursively create devices for all the child nodes, no? > +it is a lot of mucking about for just registering platform devices. > + -- Regards, Shawn -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
