Re: [PATCH v3 07/19] dt-bindings: memory: factorise LPDDR channel binding into memory channel

[Krzysztof Kozlowski <krzk@kernel.org>]

On Tue, Jul 22, 2025 at 04:03:24PM +0200, Clément Le Goffic wrote:
> LPDDR and DDR channels exist and share the same properties, they have a
> compatible, ranks, and an io-width.

Maybe it is true for all types of SDRAM, like RDRAM and eDRAM, but I
don't think all memory types do.

I think this should be renamed to sdram-channel.

> 
> Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
> ---
>  ...pddr-channel.yaml => jedec,memory-channel.yaml} | 26 +++++++++++-----------
>  1 file changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-channel.yaml b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,memory-channel.yaml
> similarity index 82%
> rename from Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-channel.yaml
> rename to Documentation/devicetree/bindings/memory-controllers/ddr/jedec,memory-channel.yaml
> index 34b5bd153f63..3bf3a63466eb 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,lpddr-channel.yaml
> +++ b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,memory-channel.yaml
> @@ -1,16 +1,16 @@
>  # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>  %YAML 1.2
>  ---
> -$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,lpddr-channel.yaml#
> +$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,memory-channel.yaml#
>  $schema: http://devicetree.org/meta-schemas/core.yaml#
>  
> -title: LPDDR channel with chip/rank topology description
> +title: Memory channel with chip/rank topology description
>  
>  description:
> -  An LPDDR channel is a completely independent set of LPDDR pins (DQ, CA, CS,
> -  CK, etc.) that connect one or more LPDDR chips to a host system. The main
> -  purpose of this node is to overall LPDDR topology of the system, including the
> -  amount of individual LPDDR chips and the ranks per chip.
> +  A memory channel is a completely independent set of pins (DQ, CA, CS,

A memory channel of SDRAM memory like DDR SDRAM or LPDDR SDRAM is ...

> +  CK, etc.) that connect one or more memory chips to a host system. The main
> +  purpose of this node is to overall memory topology of the system, including the
> +  amount of individual memory chips and the ranks per chip.
>  
>  maintainers:
>    - Julius Werner <jwerner@chromium.org>
> @@ -26,14 +26,14 @@ properties:
>    io-width:
>      description:
>        The number of DQ pins in the channel. If this number is different
> -      from (a multiple of) the io-width of the LPDDR chip, that means that
> +      from (a multiple of) the io-width of the memory chip, that means that
>        multiple instances of that type of chip are wired in parallel on this
>        channel (with the channel's DQ pins split up between the different
>        chips, and the CA, CS, etc. pins of the different chips all shorted
>        together).  This means that the total physical memory controlled by a
>        channel is equal to the sum of the densities of each rank on the
> -      connected LPDDR chip, times the io-width of the channel divided by
> -      the io-width of the LPDDR chip.
> +      connected memory chip, times the io-width of the channel divided by
> +      the io-width of the memory chip.
>      enum:
>        - 8
>        - 16
> @@ -51,8 +51,8 @@ patternProperties:
>    "^rank@[0-9]+$":
>      type: object
>      description:
> -      Each physical LPDDR chip may have one or more ranks. Ranks are
> -      internal but fully independent sub-units of the chip. Each LPDDR bus
> +      Each physical memory chip may have one or more ranks. Ranks are
> +      internal but fully independent sub-units of the chip. Each memory bus
>        transaction on the channel targets exactly one rank, based on the
>        state of the CS pins. Different ranks may have different densities and
>        timing requirements.
> @@ -107,7 +107,7 @@ additionalProperties: false
>  
>  examples:
>    - |
> -    lpddr-channel0 {
> +    memory-channel0 {

If doing this, then separate commit based on generic node name
convention. But then we need to come with generic node name first,
sdram-channel?

And also '-0', not '0' suffix.

Best regards,
Krzysztof