On Mon, Nov 01, 2021 at 05:19:20PM +1100, David Gibson wrote:
> On Mon, Sep 27, 2021 at 02:04:56PM +0000, Vincent Pelletier wrote:
> > (please keep me cc'ed in replies)
> >
> > Hello,
> >
> > I suspect this may be a dtc bug, but I am not too familiar with
> > devicetree specs to tell.
> >
> > Here is a simplified example reproducing this issue:
> >
> > (SNIP)
> > /dts-v1/;
> > /plugin/;
> >
> > / {
> > compatible = "foo";
> > };
> >
> > &{/soc/gpio@7e200000} {
> > status = "okay";
> > };
> >
> > &{/soc/spi@7e204000} {
> > cs-gpios = <&{/soc/gpio@7e200000} 8 0x01>;
> > };
> > (SNIP)
> >
> > This code builds fine:
> > $ dtc -I dts -O dtb -o test.dtbo test.dts
> > $
> > But then when disassembling the output, I get:
> > $ dtc -I dtb -O dts test.dtbo
> > <stdout>: ERROR (property_name_chars): /__fixups__:/soc/gpio@7e200000: Bad character '/' in property name
> > ERROR: Input tree has errors, aborting (use -f to force output)
> > And forcing output:
> > $ dtc -I dtb -O dts -f test.dtbo
> > <stdout>: ERROR (property_name_chars): /__fixups__:/soc/gpio@7e200000: Bad character '/' in property name
> > Warning: Input tree has errors, output forced
> > /dts-v1/;
> >
> > / {
> > compatible = "foo";
> >
> > fragment@0 {
> > target-path = "/soc/gpio@7e200000";
> >
> > __overlay__ {
> > status = "okay";
> > };
> > };
> >
> > fragment@1 {
> > target-path = "/soc/spi@7e204000";
> >
> > __overlay__ {
> > cs-gpios = <0xffffffff 0x08 0x01>;
> > };
> > };
> >
> > __fixups__ {
> > /soc/gpio@7e200000 = "/fragment@1/__overlay__:cs-gpios:0";
> > };
> > };
> >
> > Indeed, the node in __fixups__ has an invalid name.
> >
> > I suspect this is uncommon because:
> > - it probably only occurs in overlays and not in self-contained trees,
> > as a self-contained tree would likely produce an internal phandle and
> > never store the full path anywhere.
> > - ...which does not attach to labels but full paths
> > Labels being (probably ?) valid node names, they would avoid the issue.
> > - ...in arrays
> > In a node overlay, the full path ends up as a quoted string, not as a
> > name, so it is safe.
> >
> > Is this a dtc bug ?
>
> I've looked at this again and... not really.
>
> Unfortunately, such a reference can't work given the specification of
> the overlay format. The property name in fixups is the target of the
> reference, which works fine for labels, but will necessarily result in
> an invalid property name for path references.
>
> dtc should, of course, have a less ugly failure mode.
I finally got a chance to tackle this, and just sent out a patch which
should make this case fail on attempting to build the dtbo in the
first place, rather than later when processing the bad output.
--
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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