Simon, Stephen, On Tue, Oct 11, 2011 at 04:54:27PM -0700, Simon Glass wrote: > Hi Stephen, > > On Tue, Oct 11, 2011 at 4:37 PM, Stephen Warren <swar...@nvidia.com> wrote: > > Simon Glass wrote at Tuesday, October 11, 2011 4:26 PM: > > ... > >> and add some defines to your board (only ARM is currently supported): > >> > >> #define CONFIG_OF_CONTROL (to enable run-time config control via > >> fdt) > >> #define CONFIG_OF_EMBED or CONFIG_OF_SEPARATE > >> (either build the fdt blob into U-Boot, or create a separate u-boot.dtb > >> and u-boot-dtb.bin) > >> #define CONFIG_DEFAULT_DEVICE_TREE "<your name>" > >> (to specify the name of the device tree file is > >> board/<vendor>/dts/<your name>.dts) > >> > >> Typically a CPU device tree include file is provided which defines all the > >> devices available on that CPU/SOC, with each set to 'status = "disabled"'. > >> Board device tree files should adjust only the devices they use, setting > >> 'status = 'ok"' in each case, and leaving the existing devices alone and > >> disabled. ... > > > > In the Linux kernel, things used to work exactly as described above, but > > the kernel has switched to having no "status" properties in the SoC base > > file (and hence everything defaults to enabled), with the per-board .dts > > files set 'status = "disabled"' where desired. I imagine U-Boot should > > follow the same practice. > > > > I forget the exact reason for this in the kernel; it may simply have been > > due to precedent on PowerPC. Grant Likely would know the details. > > Well it's going to create a bit of work for boards that use only a > subset of these 30-peripheral SOCs, but perhaps the expectation is > that you would be buying a simpler SOC if you didn't need all the > features.
I imagine u-boot's methodology of loading drivers only as needed will prevent the unnecessary initialization of 30 drivers which are default 'status = "enabled";'. Or, am I missing something? thx, Jason. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
