linux-kernel - [PATCH v3 3/6] PCI: Add new start_link() & stop

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Message-ID: <20241112-qps615_pwr-v3-3-29a1e98aa2b0@quicinc.com>
Date: Tue, 12 Nov 2024 20:31:35 +0530
From: Krishna chaitanya chundru <quic_krichai@...cinc.com>
To: <andersson@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
        "Lorenzo
 Pieralisi" <lpieralisi@...nel.org>,
        Krzysztof Wilczyński
	<kw@...ux.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        "Rob Herring" <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        "Conor Dooley" <conor+dt@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        <cros-qcom-dts-watchers@...omium.org>,
        Jingoo Han <jingoohan1@...il.com>, Bartosz Golaszewski <brgl@...ev.pl>
CC: <quic_vbadigan@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Krishna chaitanya chundru
	<quic_krichai@...cinc.com>
Subject: [PATCH v3 3/6] PCI: Add new start_link() & stop_link function ops

Certain devices like QPS615 which uses PCI pwrctl framework
needs to configure the device before PCI link is up.

If the controller driver already enables link training as part of
its probe, after the device is powered on, controller and device
participates in the link training and link can come up immediately
and maynot have time to configure the device.

So we need to stop the link training by using stop_link() and enable
them back after device is configured by using start_link().

Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
---
 include/linux/pci.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 573b4c4c2be6..fe6a9b4b22ee 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -806,6 +806,8 @@ struct pci_ops {
 	void __iomem *(*map_bus)(struct pci_bus *bus, unsigned int devfn, int where);
 	int (*read)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val);
 	int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);
+	int (*start_link)(struct pci_bus *bus);
+	void (*stop_link)(struct pci_bus *bus);
 };
 
 /*

-- 
2.34.1