On Tue, Feb 11, 2020 at 02:29:22PM -0600, Rob Herring wrote: > On Mon, Feb 10, 2020 at 5:44 PM David Gibson > <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Mon, Feb 10, 2020 at 12:40:19PM +0100, Marek Szyprowski wrote: > > > Hi David, > > > > > > On 05.02.2020 06:45, David Gibson wrote: > > > > On Tue, Feb 04, 2020 at 01:58:44PM +0100, Marek Szyprowski wrote: > > > >> While applying dt-overlays using libfdt code, the order of the applied > > > >> properties and sub-nodes is reversed. This should not be a problem in > > > >> ideal world (mainline), but this matters for some vendor specific/custom > > > >> dtb files. This can be easily fixed by the little change to libfdt code: > > > >> any new properties and sub-nodes should be added after the parent's node > > > >> properties and subnodes. > > > >> > > > >> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > > > > I'm not convinced this is a good idea. > > > > > > > > First, anything that relies on the order of properties or subnodes in > > > > a dtb is deeply, fundamentally broken. That can't even really be a > > > > problem with a dtb file itself, only with the code processing it. > > > > > > I agree about the properties, but generally the order of nodes usually > > > implies the order of creation of some devices or objects. > > > > Huh? From the device tree client's point of view the devices just > > exist - the order of creation should not be visible to it. > > I'm not sure if downstream is different, but upstream this stems from > Linux initcalls being processed in link order within a given level. > It's much better than it used to be, but short of randomizing the > ordering, I'm not sure we'll ever find and fix all these hidden > dependencies. Uhh... I don't really see how that relates to device tree encoding order. That's another source of non-stable device identifications, which dtb order can also be, but they're not really connected beyond that as far as I can tell. > > > This sometimes > > > has some side-effects. > > > > If those side effects matter, your code is broken. If you need to > > apply an order to nodes, you should be looking at 'reg' or other > > properties. > > The general preference is to sort by 'reg'. And we try to catch and > reject any node re-ordering patches. > > Rob > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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