linux-kernel - [PATCH 08/13] PCI: MSI: Let PCI host bridges declare their lack of MSI handling

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Message-Id: <20210225151023.3642391-9-maz@kernel.org>
Date:   Thu, 25 Feb 2021 15:10:18 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Frank Wunderlich <frank-w@...lic-files.de>,
        Thierry Reding <treding@...dia.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh@...nel.org>, Will Deacon <will@...nel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Michal Simek <michal.simek@...inx.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-hyperv@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org
Subject: [PATCH 08/13] PCI: MSI: Let PCI host bridges declare their lack of MSI handling

From: Thomas Gleixner <tglx@...utronix.de>

Some PCI host bridges cannot deal with MSIs at all. This has
the unfortunate effect of triggering ugly warnings when an end-point
driver requests MSIs.

Instead, let the bridge advertise such lack of MSIs, so that it
can be flagged correctly by the core code.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/pci/probe.c | 2 ++
 include/linux/pci.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index fb04fc81a8bd..146bd85c037e 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -925,6 +925,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	device_enable_async_suspend(bus->bridge);
 	pci_set_bus_of_node(bus);
 	pci_set_bus_msi_domain(bus);
+	if (bridge->no_msi)
+		bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
 
 	if (!parent)
 		set_dev_node(bus->bridge, pcibus_to_node(bus));
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 105ef1a5191e..9db3abf9fd90 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -550,6 +550,7 @@ struct pci_host_bridge {
 	unsigned int	native_dpc:1;		/* OS may use PCIe DPC */
 	unsigned int	preserve_config:1;	/* Preserve FW resource setup */
 	unsigned int	size_windows:1;		/* Enable root bus sizing */
+	unsigned int	no_msi:1;		/* Bridge has no MSI support */
 
 	/* Resource alignment requirements */
 	resource_size_t (*align_resource)(struct pci_dev *dev,
-- 
2.29.2