linux-kernel - [PATCH 3/9] PCI/switchtec: Add module parameter to request more interrupts

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Message-Id: <20190131185656.17972-4-logang@deltatee.com>
Date:   Thu, 31 Jan 2019 11:56:50 -0700
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-ntb@...glegroups.com,
        linux-pci@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kselftest@...r.kernel.org, Jon Mason <jdmason@...zu.us>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Allen Hubbe <allenbh@...il.com>, Dave Jiang <dave.jiang@...el.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Eric Pilmore <epilmore@...aio.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH 3/9] PCI/switchtec: Add module parameter to request more interrupts

Seeing the we want to use more interrupts in the NTB MSI code
we need to be able allocate more (sometimes virtual) interrupts
in the switchtec driver. Therefore add a module parameter to
request to allocate additional interrupts.

This puts virtually no limit on the number of MSI interrupts available
to NTB clients.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/switch/switchtec.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index e22766c79fe9..8b1db78197d9 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -30,6 +30,10 @@ module_param(use_dma_mrpc, bool, 0644);
 MODULE_PARM_DESC(use_dma_mrpc,
 		 "Enable the use of the DMA MRPC feature");
 
+static int nirqs = 32;
+module_param(nirqs, int, 0644);
+MODULE_PARM_DESC(nirqs, "number of interrupts to allocate (more may be useful for NTB applications)");
+
 static dev_t switchtec_devt;
 static DEFINE_IDA(switchtec_minor_ida);
 
@@ -1247,8 +1251,12 @@ static int switchtec_init_isr(struct switchtec_dev *stdev)
 	int dma_mrpc_irq;
 	int rc;
 
-	nvecs = pci_alloc_irq_vectors(stdev->pdev, 1, 4,
-				      PCI_IRQ_MSIX | PCI_IRQ_MSI);
+	if (nirqs < 4)
+		nirqs = 4;
+
+	nvecs = pci_alloc_irq_vectors(stdev->pdev, 1, nirqs,
+				      PCI_IRQ_MSIX | PCI_IRQ_MSI |
+				      PCI_IRQ_VIRTUAL);
 	if (nvecs < 0)
 		return nvecs;
 
-- 
2.19.0