linux-kernel - Re: [PATCH v3 3/4] PCI: qcom: Parse PERST# from all PCIe bridge nodes

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Message-ID: <20250912232811.GA1653368@bhelgaas>
Date: Fri, 12 Sep 2025 18:28:11 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Manivannan Sadhasivam <mani@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Saravana Kannan <saravanak@...gle.com>, linux-pci@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
	Brian Norris <briannorris@...omium.org>
Subject: Re: [PATCH v3 3/4] PCI: qcom: Parse PERST# from all PCIe bridge nodes

On Fri, Sep 12, 2025 at 02:05:03PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> 
> Devicetree schema allows the PERST# GPIO to be present in all PCIe bridge
> nodes, not just in Root Port node. But the current logic parses PERST# only
> from the Root Port nodes. Though it is not causing any issue on the current
> platforms, the upcoming platforms will have PERST# in PCIe switch
> downstream ports also. So this requires parsing all the PCIe bridge nodes
> for the PERST# GPIO.
> 
> Hence, rework the parsing logic to extend to all PCIe bridge nodes starting
> from the Root Port node. If the 'reset-gpios' property is found for a PCI
> bridge node, the GPIO descriptor will be stored in qcom_pcie_perst::desc
> and added to the qcom_pcie_port::perst list.

The switch part doesn't seem qcom specific.  Aren't we going to end up
with lots of drivers reimplementing something like the
qcom_pcie_port.perst list?