Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20201211144236.3825-1-nadeem@cadence.com> <20201211144236.3825-2-nadeem@cadence.com>
In-Reply-To: <20201211144236.3825-2-nadeem@cadence.com>
From:   Rob Herring <robh@kernel.org>
Date:   Fri, 11 Dec 2020 11:02:26 -0600
Message-ID: <CAL_JsqLTz2k03gzrjDqi2d1NHQV+3pXxg6OqwcJ17CmfGYMf-A@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] dt-bindings: pci: Retrain Link to work around Gen2
 training defect.
To:     Nadeem Athani <nadeem@cadence.com>
Cc:     Tom Joseph <tjoseph@cadence.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        PCI <linux-pci@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        devicetree@vger.kernel.org, Milind Parab <mparab@cadence.com>,
        Swapnil Kashinath Jakhade <sjakhade@cadence.com>,
        pthombar@cadence.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Dec 11, 2020 at 9:03 AM Nadeem Athani <nadeem@cadence.com> wrote:
>
> Cadence controller will not initiate autonomous speed change if strapped as
> Gen2. The Retrain Link bit is set as quirk to enable this speed change.
> Adding a quirk flag based on a new compatible string.
>
> Signed-off-by: Nadeem Athani <nadeem@cadence.com>
> ---
>  Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> index 293b8ec318bc..204d78f9efe3 100644
> --- a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> +++ b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> @@ -15,7 +15,9 @@ allOf:
>
>  properties:
>    compatible:
> -    const: cdns,cdns-pcie-host
> +    enum:
> +        - cdns,cdns-pcie-host
> +        - cdns,cdns-pcie-host-quirk-retrain

So, we'll just keep adding quirk strings on to the compatible? I don't
think so. Compatible strings should map to a specific
implementation/platform and quirks can then be implied from them. This
is the only way we can implement quirks in the OS without firmware
(DT) changes.

Rob