Re: [PATCH v5 1/2] dt-bindings: mfd: syscon: Add ti,j721e-acspcie-proxy-ctrl compatible

[Rob Herring <robh@kernel.org>]

On Fri, Jan 10, 2025 at 11:03:30AM +0100, Romain Naour wrote:
> From: Romain Naour <romain.naour@skf.com>
> 
> The ACSPCIE_PROXY_CTRL registers within the CTRL_MMR space of TI's J721e
> SoC are used to drive the reference clock to the PCIe Endpoint device via
> the PAD IO Buffers. Add the compatible for allowing the PCIe driver to
> obtain the regmap for the ACSPCIE_CTRL register within the System
> Controller device-tree node in order to enable the PAD IO Buffers.
> 
> Using the ti,j721e-acspcie-proxy-ctrl compatible imply to use "Proxy1"
> address (1A090h) instead of "Proxy0" (18090h) to access
> CTRLMMR_ACSPCIE0_CTRL register:
> 
>   CTRLMMR_ACSPCIE0_CTRL Register (Proxy0 Offset = 18090h; Proxy1 Offset = 1A090h)
> 
> "Proxy0" is used as the default access path that can be locked with the
> help of "CTRLMMR_LOCK0_KICK0" and "CTRLMMR_LOCK0_KICK1" registers.
> 
> The Technical Reference Manual for J721e SoC with details of the
> ASCPCIE_CTRL registers is available at:
> https://www.ti.com/lit/zip/spruil1
> 
> Signed-off-by: Romain Naour <romain.naour@skf.com>
> ---
> v5:
>   - Add missing change to the J721e system controller binding
>     to avoid DT check warning when the new acspcie0_proxy_ctrl (syscon)
>     will be added to J721e system controller node (Andrew Davis).
> 
>   https://lore.kernel.org/linux-devicetree/90f47fae-a493-471d-8fe6-e7df741161be@ti.com/
> 
>   - Explain why "Proxy1" address (1A090h) should be used while using
>     ti,j721e-acspcie-proxy-ctrl compatible (Siddharth Vadapalli).
> 
>   https://lore.kernel.org/linux-devicetree/begojbvvrpyjfr3pye7mqwiw73ucw5ynepdfujssr4jx4vs33a@pwahnph3qesl/
> 
> v4: Add missing change in the second list (From Andrew Davis) [1]
>   Rebase after the ti,j784s4-acspcie-proxy-ctrl compatible fix [2]
>   [1] https://lore.kernel.org/linux-devicetree/20250103174524.28768-1-afd@ti.com/
>   [2] https://lore.kernel.org/linux-devicetree/20250103174524.28768-2-afd@ti.com/
> 
> v3: new commit
> ---
>  Documentation/devicetree/bindings/mfd/syscon.yaml           | 2 ++
>  .../bindings/soc/ti/ti,j721e-system-controller.yaml         | 6 ++++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/syscon.yaml b/Documentation/devicetree/bindings/mfd/syscon.yaml
> index 0e68c69e7bc9..1f3e67f432e7 100644
> --- a/Documentation/devicetree/bindings/mfd/syscon.yaml
> +++ b/Documentation/devicetree/bindings/mfd/syscon.yaml
> @@ -115,6 +115,7 @@ select:
>            - ti,am625-dss-oldi-io-ctrl
>            - ti,am62p-cpsw-mac-efuse
>            - ti,am654-dss-oldi-io-ctrl
> +          - ti,j721e-acspcie-proxy-ctrl
>            - ti,j784s4-acspcie-proxy-ctrl
>            - ti,j784s4-pcie-ctrl
>            - ti,keystone-pllctrl
> @@ -213,6 +214,7 @@ properties:
>            - ti,am625-dss-oldi-io-ctrl
>            - ti,am62p-cpsw-mac-efuse
>            - ti,am654-dss-oldi-io-ctrl

> +          - ti,j721e-acspcie-proxy-ctrl
>            - ti,j784s4-acspcie-proxy-ctrl

How do these 2 compare? Are they compatible?

>            - ti,j784s4-pcie-ctrl
>            - ti,keystone-pllctrl
> diff --git a/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml b/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
> index 378e9cc5fac2..16929218d611 100644
> --- a/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
> +++ b/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
> @@ -68,6 +68,12 @@ patternProperties:
>      description:
>        The node corresponding to SoC chip identification.
>  
> +  "^syscon@[0-9a-f]+$":
> +    type: object
> +    $ref: /schemas/mfd/syscon.yaml#
> +    description:
> +      This is the ASPCIe control region.

So this is a syscon child of a syscon. The primary reason for 'syscon' 
compatible is to create a regmap. Why can't you use the parent's syscon?

Rob