On 15.07.2022 17:02, Rob Herring wrote:
On Fri, Jul 15, 2022 at 5:59 AM Rafał Miłecki <zajec5@xxxxxxxxx> wrote:
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.
Yes, you should. The parent node of a node with 'reg' must have
#address-cells and #size-cells. Simple as that.
For "parent node of a node with 'reg'" it's obvious. We have a different
case here though.
Please take one more look. Node named "partitions" does not have "reg".
That is what I don't have #foo-cells in the nand@0.
A complete example:
nand-controller@1800 {
...
#address-cells = <1>;
#size-cells = <0>;
nand@0 {
compatible = "brcm,nandcs";
reg = <0>;
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>;
};
};
};
};
It is 'ranges' that determines if addresses are translatable or not.
