linux-kernel - [PATCH v2 5/8] PCI: Add new start_link() & stop

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Message-ID: <20240803-qps615-v2-5-9560b7c71369@quicinc.com>
Date: Sat, 3 Aug 2024 08:52:51 +0530
From: Krishna chaitanya chundru <quic_krichai@...cinc.com>
To: 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>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        <cros-qcom-dts-watchers@...omium.org>,
        "Bartosz
 Golaszewski" <brgl@...ev.pl>,
        Jingoo Han <jingoohan1@...il.com>,
        "Manivannan
 Sadhasivam" <manivannan.sadhasivam@...aro.org>
CC: <andersson@...nel.org>, <quic_vbadigan@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Bartosz
 Golaszewski" <bartosz.golaszewski@...aro.org>,
        Krishna chaitanya chundru
	<quic_krichai@...cinc.com>
Subject: [PATCH v2 5/8] 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 4cf89a4b4cbc..0791d74951e9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -802,6 +802,8 @@ 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