Hi Tom, On 27 October 2014 08:24, Tom Rini <tr...@ti.com> wrote: > On Fri, Oct 24, 2014 at 02:04:00PM -0600, Simon Glass wrote: >> Hi Tom, >> >> On 24 October 2014 12:49, Tom Rini <tr...@ti.com> wrote: >> > On Thu, Oct 23, 2014 at 06:58:50PM -0600, Simon Glass wrote: >> > >> >> From: Michael Pratt <mpr...@chromium.org> >> >> >> >> Support a default memory bank, specified in reg, as well as >> >> board-specific memory banks in subtree board-id nodes. >> >> >> >> This allows memory information to be provided in the device tree, >> >> rather than hard-coded in, which will make it simpler to handle >> >> similar devices with different memory banks, as the board-id values >> >> or masks can be used to match devices. >> > [snip] >> >> +++ b/doc/device-tree-bindings/memory/memory.txt >> >> @@ -0,0 +1,67 @@ >> >> +* Memory binding >> >> + >> >> +The memory binding for U-Boot is as in the ePAPR with the following >> >> additions: >> > >> > I am wary of being different from ePAPR / Linux Kernel. What do we need >> > this for / when do we use it? >> >> This extends the existing binding. It allows the location and size of >> memory to be set by a board ID. Unfortunately on sopme hardware you >> get a hang if you try to access memory that doesn't exist, so this >> allows the range of available memory to be defined - or at least the >> maximum bound since we still probe the memory size within that range. >> >> This feature is used on several Exynos Chromebooks. > > So that you can use the same DT on several disjoint boards? How does > this work with the kernel, does U-Boot then pass along only the correct > map? Patches to the kernel to also deal with this?
Typically a board may have variants with different amounts of memory, detected at run-time by GPIOs. We want the option of using the same DT for these, similar to what the Compulab people were talking about - otherwise we have something of an explosion of combinations. Yes U-Boot (already) puts the correct memory map together for the kernel, so it all works from start to finish. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
