linux-kernel - Re: [PATCH v3 4/7] dt-bindings: PCI: dwc: add DMA, region mask bits

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Message-ID: <6dfde695-16d5-57ac-fbdd-b86ec91322a9@linaro.org>
Date:   Thu, 23 Feb 2023 19:12:17 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Elad Nachman <enachman@...vell.com>, thomas.petazzoni@...tlin.com,
        bhelgaas@...gle.com, lpieralisi@...nel.org, robh@...nel.org,
        kw@...ux.com, krzysztof.kozlowski+dt@...aro.org,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/7] dt-bindings: PCI: dwc: add DMA, region mask bits

On 23/02/2023 19:05, Elad Nachman wrote:
> From: Elad Nachman <enachman@...vell.com>
> 
> Add properties to support configurable DMA mask bits
> and region mask bits.
> configurable DMA mask bits is needed for Marvell AC5/AC5X SOCs which
> have their physical DDR memory start at address 0x2_0000_0000.
> Configurable region mask bits is needed for the Marvell Armada
> 7020/7040/8040 SOCs when the DT file places the PCIe window above the
> 4GB region.
> The Synopsis Designware PCIe IP in these SOCs is too old to specify the
> highest memory location supported by the PCIe, but practically supports
> such locations. Allow these locations to be specified in the DT file.

This formatting is so bad it makes difficult to read. Make these proper
sentences with proper wrapping.


> First DT property is called num-dmamask,
> and can range between 33 and 64.

Wrong mapping and we see it in the code. No need to code it again in
commit msg. Especially that you already said it in the first sentence.

> Second DT property is called num-regionmask,
> and can range between 33 and 64.


> 
> Signed-off-by: Elad Nachman <enachman@...vell.com>
> ---
>  .../devicetree/bindings/pci/snps,dw-pcie-common.yaml   | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> index d87e13496834..a1b06ff19ca7 100644
> --- a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> @@ -261,6 +261,16 @@ properties:
>  
>    dma-coherent: true
>  
> +  num-dmamask:
> +    description: |
> +      number of dma mask bits to use, if different than default 32

minimum: 33 (from commit msg)
default: 32... which does not make now sense...

> +    maximum: 64
> +
> +  num-regionmask:
> +    description: |
> +      number of region limit mask bits to use, if different than default 32
> +    maximum: 64
> +
>  additionalProperties: true
>  
>  ...

Best regards,
Krzysztof