On 26/10/2024 at 13:23:46 +0530, Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxx> wrote:
> This approach was suggested by Rob [1] during a discussion on Miquel's
> initial approach [2] to extend the MTD-CONCAT driver to support stacked
> memories.
> Define each flash node separately with its respective partitions, and add
> a 'concat-parts' binding to link the partitions of the two flash nodes that
> need to be concatenated.
>
> flash@0 {
> compatible = "jedec,spi-nor"
> ...
> partitions {
Wrong indentation here and below which makes the example hard to read.
> compatible = "fixed-partitions";
> concat-partition = <&flash0_partition &flash1_partition>;
> flash0_partition: partition@0 {
> label = "part0_0";
> reg = <0x0 0x800000>;
> }
> }
> }
> flash@1 {
> compatible = "jedec,spi-nor"
> ...
> partitions {
> compatible = "fixed-partitions";
> concat-partition = <&flash0_partition &flash1_partition>;
> flash1_partition: partition@0 {
> label = "part0_1";
> reg = <0x0 0x800000>;
> }
> }
> }
This approach has a limitation I didn't think about before: you cannot
use anything else than fixed partitions as partition parser.
> Based on the bindings the MTD-CONCAT driver need to be updated to create
> virtual mtd-concat devices.
>
> [1] https://lore.kernel.org/all/20191118221341.GA30937@bogus/
> [2] https://lore.kernel.org/all/20191113171505.26128-4-miquel.raynal@xxxxxxxxxxx/
>
> Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxx>
> ---
> .../mtd/partitions/fixed-partitions.yaml | 18 ++++++++++++++++++
> .../bindings/mtd/partitions/partitions.yaml | 6 ++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml b/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
> index 058253d6d889..df4ccb3dfeba 100644
> --- a/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
> +++ b/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
> @@ -183,3 +183,21 @@ examples:
> read-only;
> };
> };
> +
> + - |
> + partitions {
> + compatible = "fixed-partitions";
> + #address-cells = <1>;
> + #size-cells = <1>;
This is not strictly related but I believe we will soon have issues with
these, as we will soon cross the 4GiB boundary.
> + concat-parts = <&part0 &part1>;
> +
> + part0: partition@0 {
> + label = "flash0-part0";
> + reg = <0x0000000 0x100000>;
> + };
> +
> + part1: partition@100000 {
> + label = "flash1-part0";
> + reg = <0x0100000 0x200000>;
> + };
> + };
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/partitions.yaml b/Documentation/devicetree/bindings/mtd/partitions/partitions.yaml
> index 1dda2c80747b..86bbd83c3f6d 100644
> --- a/Documentation/devicetree/bindings/mtd/partitions/partitions.yaml
> +++ b/Documentation/devicetree/bindings/mtd/partitions/partitions.yaml
> @@ -32,6 +32,12 @@ properties:
> '#size-cells':
> enum: [1, 2]
>
> + concat-parts:
> + description: List of MTD partitions phandles that should be concatenated.
> + $ref: /schemas/types.yaml#/definitions/phandle-array
> + minItems: 2
> + maxItems: 4
> +
> patternProperties:
> "^partition(-.+|@[0-9a-f]+)$":
> $ref: partition.yaml
Fine by me otherwise.
Thanks,
Miquèl
