Re: [PATCH V1 1/4] dt-bindings: Add "hotplug-gpios" PCIe property

From: Lukas Wunner
Date: Sat Oct 01 2022 - 11:56:37 EST

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?