linux-kernel - [RFC 2/4] PCI, MSI: Optionally free legacy PCI IRQ when enabling MSI/MSI-X

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Message-Id: <1430968374-29286-3-git-send-email-jiang.liu@linux.intel.com>
Date:	Thu,  7 May 2015 11:12:52 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Lv Zheng <lv.zheng@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, "x86 @ kernel . org" <x86@...nel.org>
Subject: [RFC 2/4] PCI, MSI: Optionally free legacy PCI IRQ when enabling MSI/MSI-X

Once PCI MSI/MSI-X is enabled by the device driver, PCI device won't
make use of legacy PCI IRQ until PCI MSI/MSI-X is disabled again.
So optionally free legacy PCI IRQ when enabling MSI/MSI-X and reallocate
when disabling MSI/MSI-X.

Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
---
 drivers/pci/msi.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index c3e7dfcf9ff5..47cf72c669f0 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -686,6 +686,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
 	msi_set_enable(dev, 1);
 	dev->msi_enabled = 1;
 
+	pcibios_free_irq(dev);
 	dev->irq = entry->irq;
 	return 0;
 }
@@ -813,9 +814,10 @@ static int msix_capability_init(struct pci_dev *dev,
 	/* Set MSI-X enabled bits and unmask the function */
 	pci_intx_for_msi(dev, 0);
 	dev->msix_enabled = 1;
-
 	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 
+	pcibios_free_irq(dev);
+
 	return 0;
 
 out_avail:
@@ -930,6 +932,7 @@ void pci_msi_shutdown(struct pci_dev *dev)
 
 	/* Restore dev->irq to its default pin-assertion irq */
 	dev->irq = desc->msi_attrib.default_irq;
+	pcibios_alloc_irq(dev);
 }
 
 void pci_disable_msi(struct pci_dev *dev)
@@ -1030,6 +1033,7 @@ void pci_msix_shutdown(struct pci_dev *dev)
 	msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
 	pci_intx_for_msi(dev, 1);
 	dev->msix_enabled = 0;
+	pcibios_alloc_irq(dev);
 }
 
 void pci_disable_msix(struct pci_dev *dev)
-- 
1.7.10.4

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