[RFC][PATCH v3 1/3] dt-bindings: imx6q-pcie: Handle various clock configurations

[Krzysztof Kozlowski]

On 04/11/2022 18:04, Marek Vasut wrote:
> The i.MX SoCs have various clock configurations routed into the PCIe IP,
> the list of clock is below. Document all those configurations in the DT
> binding document.
> 
> All SoCs: pcie, pcie_bus
> 6QDL, 7D: + pcie_phy
> 6SX:      + pcie_phy          pcie_inbound_axi
> 8MQ:      + pcie_phy pcie_aux
> 8MM, 8MP: +          pcie_aux
> 
> Acked-by: Alexander Stein <alexander.stein at ew.tq-group.com>
> Signed-off-by: Marek Vasut <marex at denx.de>
> ---
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt at linaro.org>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: Richard Zhu <hongxing.zhu at nxp.com>
> Cc: Rob Herring <robh+dt at kernel.org>
> Cc: Shawn Guo <shawnguo at kernel.org>
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: NXP Linux Team <linux-imx at nxp.com>
> To: devicetree at vger.kernel.org
> ---
> V2: - Add AB from Alex
> V3: - Duplicate clock-names maxItems to mx6sx and mx8mq compatibles
>     - Flatten the if-else structure
>     - The validation no longer works and introduces errors like these:
>       arch/arm64/boot/dts/freescale/imx8mm-verdin-wifi-dahlia.dtb: pcie at 33800000: clock-names:2: 'pcie_phy' was expected
> ---
>  .../bindings/pci/fsl,imx6q-pcie.yaml          | 55 +++++++++++++++++--
>  1 file changed, 50 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
> index 376e739bcad40..44c65d3ec07b9 100644
> --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
> +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
> @@ -14,9 +14,6 @@ description: |+
>    This PCIe host controller is based on the Synopsys DesignWare PCIe IP
>    and thus inherits all the common properties defined in snps,dw-pcie.yaml.
>  
> -allOf:
> -  - $ref: /schemas/pci/snps,dw-pcie.yaml#
> -
>  properties:
>    compatible:
>      enum:
> @@ -56,12 +53,10 @@ properties:
>            imx8mq-pcie.
>  
>    clock-names:
> -    minItems: 3

Why removing this and keeping it in clocks? They must be matching each
other.

>      items:
>        - const: pcie
>        - const: pcie_bus
>        - const: pcie_phy
> -      - const: pcie_inbound_axi for imx6sx-pcie, pcie_aux for imx8mq-pcie

It's now a bit confusing - you have different items and constraints in
top-level clock-names than in if-else for specific variants.

The usual convention for this is:
1. in top-level properties add clocks and clock-names with minItems and
maxItems matching the widest possibility
2. In allOf:if:then you narrow them - with "items" or maxItems.

Your setup probably works but it is confusing. Plus I am not sure if the
names mentioned in top level clock-names are applicable now to anything...


Best regards,
Krzysztof