On Thu, Sep 20, 2012 at 5:30 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > A corner case is the one where you have different versions of the same > IP block (e.g. the pinctrl) and the kernel cannot find out which one it > is by looking at registers inside it or on the parent bus, but only > by looking at other hardware (CPU core revision, or PCI device ID of > the root complex). So this is the case I'm thinking of. We have e.g. differens small flags through platform data depending on cpu_is_ux* in the ux500. Currently we modify platform data in the board files, just as we switch some cache handling etc as we know this or that ASIC has different sized cache. > We have a precedent of at91 doing this, but I don't > like it too much because that still means having to change the driver > again if you get a new SoC with the same IP block but a different version > register, I don't like that either. > To avoid that, I'd prefer using separate "compatible" > values, at least if the hardware is already described in separate .dtsi > files. So what I'm after is whether in this case statically encoding this onto the .dtsi files is the right thing to do, or whether the boot loader or kernel should runtime-modify the device tree, patching in the ASIC-specific info, just like device tree files can override properties from include files. Or if this is a bad idea. Nobody is doing that right now AFAICT, but it is surely possible.... Yours, Linus Walleij -- 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
