Re: [PATCH v3 2/4] dt-bindings: memory: tegra20: emc: Document new LPDDR2 sub-node
From: Krzysztof Kozlowski <hidden>
Date: 2021-10-04 08:37:19
Also in:
linux-devicetree, lkml
On 03/10/2021 03:32, Dmitry Osipenko wrote:
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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@gmail.com> --- .../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-codeIsn't lpddr2-configuration required in such case? If not, probably you want either this or that (oneOf like in reserved-memory.yaml).
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- 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