Re: [PATCH 00/14] PCI: qcom: Simulate PCIe hotplug using 'global' interrupt

[Konrad Dybcio]

On 15.07.2024 7:33 PM, Manivannan Sadhasivam via B4 Relay wrote:
> Hi,
> 
> This series adds support to simulate PCIe hotplug using the Qcom specific
> 'global' IRQ. Historically, Qcom PCIe RC controllers lack standard hotplug
> support. So when an endpoint is attached to the SoC, users have to rescan the
> bus manually to enumerate the device. But this can be avoided by simulating the
> PCIe hotplug using Qcom specific way.
> 
> Qcom PCIe RC controllers are capable of generating the 'global' SPI interrupt
> to the host CPUs. The device driver can use this event to identify events such
> as PCIe link specific events, safety events etc...
> 
> One such event is the PCIe Link up event generated when an endpoint is detected
> on the bus and the Link is 'up'. This event can be used to simulate the PCIe
> hotplug in the Qcom SoCs.
> 
> So add support for capturing the PCIe Link up event using the 'global' interrupt
> in the driver. Once the Link up event is received, the bus underneath the host
> bridge is scanned to enumerate PCIe endpoint devices, thus simulating hotplug.
> 
> This series also has some cleanups to the Qcom PCIe EP controller driver for
> interrupt handling.

Welp I've reviewed this series, and only now came to the realization that
the PCIe RC and PCIe EP descriptions are borderline identical.. perhaps for
new platforms we could get a new binding that could have a structure like

pcie@abcd1234 {
	// commmon properties

	pcie-ep {
		// ep specifics
	};

	pcie-rc {
		// rc specifics
	}
};

or better yet, have a single node no matter what, but consume only the
required resources from the driver and have something akin to phy-mode,
just like we solved the DP/eDP dual-mode controller story

Although here it may not be so simple given there's properties like
iommu-map that map to bus specifics..

Konrad