On Monday 04 April 2011, Benjamin Herrenschmidt wrote: > On Fri, 2011-04-01 at 16:28 +0200, Detlef Vollmann wrote: > > > * No board files > > Where do you put code that needs to run very early (e.g. pinging the > > watchdog)? > > Even on powerpc I keep board files :-) > > The main thing is: > > - The generic -> board linkage must not be hard (ie, no > platform_restart, but a board_ops.restart() etc....) > > - An average board file is a few hundreds line long, that's it, mostly > it hooks up to generically provided functions, tho it gets the choice of > _which_ ones to hookup. I believe a machine_type is more general than a board file, i.e. what gets described as a machine in powerpc would often currently correspond to multiple board files, if I am not mistaken. The fact that we have a more diverse set of hardware on ARM, and that it's growing quicker than powerpc also means that we should try harder to reduce duplication than is necessary there. > - It can still quirk/fixup a thing or two if needed, I thinkt it's > useful to keep that around, as long as such "quirks" remain small and > few. At the end of the day, if dealing with one board special case gives > you the choice between changing a ton of infrastructure/core to > introduce a new abstraction to deal with -that- special case vs. having > a one liner fixup in the platform code, the later is the most sensible > option. The hard part of course is to have sensible maintainers to make > sure this doesn't grow back to the old mess. I guess quirks are fine, as long as it's not required to have a them for each board. We can have a function that gets called for any matching "compatible" property of the root node, but I think the default should be not to need it eventually. This is one area where I think I can illustrate how a gradual change from the status quo differs from a parallel new platform implementation: To gradually change one board file, you would convert the existing machine description to match the compatible property of the device tree root node and possibly at a later stage remove that code again once it's possible to work without it. When starting out with a fresh implementation, we first need to change all device drivers that are used on the board to work without a machine description, but then would not have to change any code twice, and the work for a similar board is almost done. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
