linux-kernel - [PATCH 2/2] pci: call pci_intx when using legacy interrupts in pci_alloc_irq

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Date:	Thu, 11 Aug 2016 07:11:05 -0700
From:	Christoph Hellwig <hch@....de>
To:	linux-pci@...r.kernel.org, helgaas@...nel.org, agordeev@...hat.com
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] pci: call pci_intx when using legacy interrupts in pci_alloc_irq_vectors

ahci currently insists on an explicit call to pci_intx before falling back
from MSI or MSI-X to legacy irqs.  As pci_intx is a no-op if the command
register already contains the right value is seems safe and useful to add
this call to pci_alloc_irq_vectors so that ahci can just use
pci_alloc_irq_vectors.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/pci/msi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 9233e7f..593698e 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1200,8 +1200,11 @@ int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
 	}
 
 	/* use legacy irq if allowed */
-	if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1)
+	if ((flags & PCI_IRQ_LEGACY) && min_vecs == 1) {
+		pci_intx(dev, 1);
 		return 1;
+	}
+
 	return vecs;
 }
 EXPORT_SYMBOL(pci_alloc_irq_vectors);
-- 
2.1.4