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Date:   Sat, 1 Oct 2022 17:56:26 +0200
From:   Lukas Wunner <lukas@wunner.de>
To:     Vidya Sagar <vidyas@nvidia.com>
Cc:     bhelgaas@google.com, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, lpieralisi@kernel.org,
        kw@linux.com, thierry.reding@gmail.com, jonathanh@nvidia.com,
        mani@kernel.org, Sergey.Semin@baikalelectronics.ru,
        jszhang@kernel.org, linux-pci@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, kthota@nvidia.com,
        mmaddireddy@nvidia.com, sagar.tv@gmail.com,
        Marek =?iso-8859-1?Q?Beh=FAn?= <kabel@kernel.org>,
        Pali =?iso-8859-1?Q?Roh=E1r?= <pali@kernel.org>,
        Jonathan Derrick <jonathan.derrick@linux.dev>
Subject: Re: [PATCH V1 1/4] dt-bindings: Add "hotplug-gpios" PCIe property
Message-ID: <20221001155626.GA9324@wunner.de>
References: <20220930192747.21471-1-vidyas@nvidia.com>
 <20220930192747.21471-2-vidyas@nvidia.com>
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On Sat, Oct 01, 2022 at 12:57:44AM +0530, Vidya Sagar wrote:
> Provide a way for the firmware to tell the OS about the GPIO that can be
> used to get the Hot-Plug and Unplug events.
[...]
> --- a/Documentation/devicetree/bindings/pci/pci.txt
> +++ b/Documentation/devicetree/bindings/pci/pci.txt
> @@ -32,6 +32,10 @@ driver implementation may support the following properties:
>     root port to downstream device and host bridge drivers can do programming
>     which depends on CLKREQ signal existence. For example, programming root port
>     not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal.
> +- hotplug-gpios:
> +   If present this property specifies the GPIO to be used for Hot-Plug/Unplug
> +   functionality. It is used by the PCIe GPIO Hot-Plug core driver for
> +   PCIe device Hot-Plug/Unplug events.

Please specify the GPIO's semantics in more detail:
Is the pin high as long as presence of a card is detected?
Or does it pulse when a hotplug/unplug event occurs?

Thanks,

Lukas