of_platform_populate() for address-less nodes (OF: Bad cell count for ...)

["Rafał Miłecki" <zajec5@gmail.com>]

I need Linux to support MTD partitions drivers. They should get probed
for MTD partitions, access it, do their stuff. Random example:

partitions {
	compatible = "fixed-partitions";
	#address-cells = <1>;
	#size-cells = <1>;

	partition@0 {
		compatible = "u-boot,bootloader";
		label = "loader";
		reg = <0x0 0x100000>;
	};

	partition@100000 {
		compatible = "u-boot,env";
		label = "image";
		reg = <0x100000 0x100000>;
	};
};

(please don't confuse them with parsers which are MTD internals)


To support that I added of_platform_populate() calls, see commit
bcdf0315a61a2 ("mtd: call of_platform_populate() for MTD partitions"):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bcdf0315a61a29eb753a607d3a85a4032de72d94


The problem I just noticed is it triggers errors like:
OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0/partitions

It comes from (forward-trace):
of_platform_populate()
of_platform_bus_create()
of_platform_device_create_pdata()
of_device_alloc()
of_address_to_resource()
of_address_to_resource()
__of_address_to_resource()
of_translate_address()
__of_translate_address()
OF_CHECK_COUNTS()
pr_err()


It's caused by "partitions" node having 1 address cell and 0 size cells.
It's a consequence of inheriting sizes from NAND CS:

nand-controller@1800 {
	...

	#address-cells = <1>;
	#size-cells = <0>;

	nand@0 {
		compatible = "brcm,nandcs";
		reg = <0>;

		partitions {
			...
		};
	};
};


Is that something that can / should be fixed in OF implementation?

I don't think I should assign sizes to "partitions" node as it doesn't
use "reg" at all. All "reg" in "partitions" subnodes contain flash
relative offsets and they should not be translated.


[    4.360609] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0/partitions/partition@0 **
[    4.370814] OF: bus is default (na=1, ns=1) on /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.380130] OF: translating address: 00000000
[    4.384609] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.392859] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0/partitions/partition@0 **
[    4.403069] OF: bus is default (na=1, ns=1) on /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.412384] OF: translating address: 00000000
[    4.416864] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.425110] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0 **
[    4.433263] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0
[    4.440520] OF: ** translation for device /bus@ff800000/nand-controller@1800 **
[    4.448044] OF: bus is default (na=1, ns=1) on /bus@ff800000
[    4.453868] OF: translating address: 00001800
[    4.458347] OF: parent bus is default (na=2, ns=2) on
[    4.463635] OF: walking ranges...
[    4.467038] OF: default map, cp=0, s=3000, da=1800
[    4.471967] OF: parent translation for: 00000000 ff800000
[    4.477521] OF: with offset: 1800
[    4.480928] OF: one level translation: 00000000 ff801800
[    4.486390] OF: reached root node
[    4.489874] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0/partitions/partition@100000 **
[    4.500465] OF: bus is default (na=1, ns=1) on /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.509776] OF: translating address: 00100000
[    4.514262] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.522509] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0/partitions/partition@100000 **
[    4.533167] OF: bus is default (na=1, ns=1) on /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.542483] OF: translating address: 00100000
[    4.546963] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0/partitions
[    4.555211] OF: ** translation for device /bus@ff800000/nand-controller@1800/nand@0 **
[    4.563362] OF: Bad cell count for /bus@ff800000/nand-controller@1800/nand@0
[    4.570620] OF: ** translation for device /bus@ff800000/nand-controller@1800 **
[    4.578142] OF: bus is default (na=1, ns=1) on /bus@ff800000
[    4.583967] OF: translating address: 00001800
[    4.588446] OF: parent bus is default (na=2, ns=2) on
[    4.593733] OF: walking ranges...
[    4.597137] OF: default map, cp=0, s=3000, da=1800
[    4.602067] OF: parent translation for: 00000000 ff800000
[    4.607619] OF: with offset: 1800
[    4.611027] OF: one level translation: 00000000 ff801800
[    4.616489] OF: reached root node