linux-kernel - Re: [PATCH 1/2] dt-bindings: PCI: designware: Add binding for ZRX-DC PHY property

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Message-ID: <20191021141541.GS47056@e119886-lin.cambridge.arm.com>
Date:   Mon, 21 Oct 2019 15:15:41 +0100
From:   Andrew Murray <andrew.murray@....com>
To:     Anvesh Salveru <anvesh.s@...sung.com>
Cc:     linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
        gustavo.pimentel@...opsys.com, jingoohan1@...il.com,
        robh+dt@...nel.org, mark.rutland@....com,
        Pankaj Dubey <pankaj.dubey@...sung.com>
Subject: Re: [PATCH 1/2] dt-bindings: PCI: designware: Add binding for ZRX-DC
 PHY property

On Mon, Oct 21, 2019 at 05:55:55PM +0530, Anvesh Salveru wrote:
> Add support for ZRX-DC compliant PHYs. If PHY is not compliant to ZRX-DC
> specification, then after every 100ms link should transition to recovery
> state during the low power states which increases power consumption.
> 
> Platforms with ZRX-DC compliant PHY can use "snps,phy-zrxdc-compliant"
> property in DesignWare controller DT node.
> 
> Signed-off-by: Anvesh Salveru <anvesh.s@...sung.com>
> Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com>
> ---
>  Documentation/devicetree/bindings/pci/designware-pcie.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/designware-pcie.txt b/Documentation/devicetree/bindings/pci/designware-pcie.txt
> index 78494c4050f7..9507ac38ac89 100644
> --- a/Documentation/devicetree/bindings/pci/designware-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/designware-pcie.txt
> @@ -38,6 +38,8 @@ Optional properties:
>     for data corruption. CDM registers include standard PCIe configuration
>     space registers, Port Logic registers, DMA and iATU (internal Address
>     Translation Unit) registers.
> +- snps,phy-zrxdc-compliant: This property is needed if phy complies with the

Strictly speaking, this is a property of the phy - not the controller that
uses it.

If I understand correctly, there are some DW based PCI controllers that use
a phandle reference in DT to a Phy (such as fsl,imx6q-pcie.txt). Therefore
it feels like this is in the wrong place. Is there a reason this isn't
described in the Phy?

Thanks,

Andrew Murray

> +  ZRX-DC specification.
>  RC mode:
>  - num-viewport: number of view ports configured in hardware. If a platform
>    does not specify it, the driver assumes 2.
> -- 
> 2.17.1
>