On 03/10/2021 03:32, Dmitry Osipenko wrote:
> Some Tegra20 boards don't have RAM code stored in NVMEM, which is used for
> the memory chip identification and the identity information should be read
> out from LPDDR2 chip in this case. Document new sub-node containing generic
> LPDDR2 properties that will be used for the memory chip identification if
> RAM code isn't available. The identification is done by reading out memory
> configuration values from generic LPDDR2 mode registers of SDRAM chip and
> comparing them with the values of device-tree sub-node's.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> .../memory-controllers/nvidia,tegra20-emc.yaml | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.yaml b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.yaml
> index cac6842dc8f1..65f7c3898ac4 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.yaml
> +++ b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.yaml
> @@ -164,13 +164,14 @@ patternProperties:
> "#size-cells":
> const: 0
>
> + lpddr2-configuration:
Nodes should be named generic, so just lpddr2?
> + $ref: "jedec,lpddr2.yaml#"
> + type: object
> +
> patternProperties:
> "^emc-table@[0-9]+$":
> $ref: "#/$defs/emc-table"
>
> - required:
> - - nvidia,ram-code
Isn't lpddr2-configuration required in such case? If not, probably you
want either this or that (oneOf like in reserved-memory.yaml).
> -
> additionalProperties: false
>
> required:
> @@ -186,6 +187,8 @@ additionalProperties: false
>
> examples:
> - |
> + #include <dt-bindings/memory/lpddr2.h>
> +
> external-memory-controller@7000f400 {
> compatible = "nvidia,tegra20-emc";
> reg = <0x7000f400 0x400>;
> @@ -226,5 +229,13 @@ examples:
> 0x007fe010 0x00001414 0x00000000 0x00000000
> 0x00000000 0x00000000 0x00000000 0x00000000>;
> };
> +
> + lpddr2-configuration {
> + jedec,lpddr2-manufacturer-id = <LPDDR2_MANID_ELPIDA>;
> + jedec,lpddr2-revision-id1 = <1>;
> + jedec,lpddr2-density-mbits = <2048>;
> + jedec,lpddr2-io-width-bits = <16>;
> + jedec,lpddr2-type = <LPDDR2_TYPE_S4>;
> + };
> };
> };
>
Best regards,
Krzysztof
