linux-kernel - Re: [PATCH 13/14] PCI: qcom: Simulate PCIe hotplug using 'global' interrupt

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Message-ID: <f1f6501c-8562-4f1a-a598-4ab58c7f44e2@linaro.org>
Date: Mon, 15 Jul 2024 22:06:58 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: manivannan.sadhasivam@...aro.org,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Bjorn Andersson <andersson@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 13/14] PCI: qcom: Simulate PCIe hotplug using 'global'
 interrupt

On 15.07.2024 7:33 PM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> 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.
> 
> All of the Qcom SoCs have only one rootport per controller instance. So
> only a single 'Link up' event is generated for the PCIe controller.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad