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Subject[PATCH 2/2] uio: Prefer MSI(X) interrupts in PCI drivers
Date

Signed-off-by: Manuel Stahl <manuel.stahl@iis.fraunhofer.de>
---
 drivers/uio/uio_pci_dmem_genirq.c | 27 ++++++++++++++++++++-------
 drivers/uio/uio_pci_generic.c     | 24 ++++++++++++++++++------
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/drivers/uio/uio_pci_dmem_genirq.c b/drivers/uio/uio_pci_dmem_genirq.c
index d1dfd8002c6d..ebb3f9012cd8 100644
--- a/drivers/uio/uio_pci_dmem_genirq.c
+++ b/drivers/uio/uio_pci_dmem_genirq.c
@@ -173,11 +173,13 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
 {
  struct uio_pci_dmem_dev *gdev = to_uio_pci_dmem_dev(info);
 
- if (!pci_check_and_mask_intx(gdev->pdev))
- return IRQ_NONE;
+ if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+ return IRQ_HANDLED;
 
- /* UIO core will signal the user process. */
- return IRQ_HANDLED;
+ if (pci_check_and_mask_intx(gdev->pdev))
+ return IRQ_HANDLED;
+
+ return IRQ_NONE;
 }
 
 static unsigned int uio_dmem_dma_bits = 32;
@@ -269,11 +271,19 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
  }
  pci_set_master(pdev);
 
- dev_info(&pdev->dev, "Legacy IRQ: %i", pdev->irq);
- if (pdev->irq && !pci_intx_mask_supported(pdev)) {
- err = -ENODEV;
+ /* Try to use MSI interrupts */
+ err = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
+ if (err) {
+ dev_err(&pdev->dev, "%s: pci_alloc_irq_vectors failed: %d\n",
+ __func__, err);
  goto err_disable_pci;
  }
+ if (!pdev->msi_enabled && !pdev->msix_enabled &&
+     !pci_intx_mask_supported(pdev)) {
+ err = -ENODEV;
+ goto err_free_irq_vectors;
+ }
+ dev_info(&pdev->dev, "IRQ: %i", pdev->irq);
 
  gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
  if (!gdev) {
@@ -316,6 +326,8 @@ static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
  return 0;
 err_free_gdev:
  kfree(gdev);
+err_free_irq_vectors:
+ pci_free_irq_vectors(pdev);
 err_disable_pci:
  pci_clear_master(pdev);
  pci_disable_device(pdev);
@@ -327,6 +339,7 @@ static void remove(struct pci_dev *pdev)
  struct uio_pci_dmem_dev *gdev = pci_get_drvdata(pdev);
 
  uio_unregister_device(&gdev->info);
+ pci_free_irq_vectors(pdev);
  pci_clear_master(pdev);
  pci_disable_device(pdev);
  kfree(gdev);
diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c
index a56fdf972dbe..23a800e76303 100644
--- a/drivers/uio/uio_pci_generic.c
+++ b/drivers/uio/uio_pci_generic.c
@@ -46,11 +46,13 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
 {
  struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
 
- if (!pci_check_and_mask_intx(gdev->pdev))
- return IRQ_NONE;
+ if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+ return IRQ_HANDLED;
 
- /* UIO core will signal the user process. */
- return IRQ_HANDLED;
+ if (pci_check_and_mask_intx(gdev->pdev))
+ return IRQ_HANDLED;
+
+ return IRQ_NONE;
 }
 
 static int probe(struct pci_dev *pdev,
@@ -66,10 +68,18 @@ static int probe(struct pci_dev *pdev,
  return err;
  }
 
- if (pdev->irq && !pci_intx_mask_supported(pdev)) {
- err = -ENODEV;
+ /* Try to use MSI interrupts */
+ err = pci_alloc_irq_vectors(pdev, 0, 1, PCI_IRQ_ALL_TYPES);
+ if (err) {
+ dev_err(&pdev->dev, "%s: pci_alloc_irq_vectors failed: %d\n",
+ __func__, err);
  goto err_verify;
  }
+ if (pdev->irq && !pdev->msi_enabled && !pdev->msix_enabled &&
+     !pci_intx_mask_supported(pdev)) {
+ err = -ENODEV;
+ goto err_alloc;
+ }
 
  gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
  if (!gdev) {
@@ -98,6 +108,7 @@ static int probe(struct pci_dev *pdev,
 err_register:
  kfree(gdev);
 err_alloc:
+ pci_free_irq_vectors(pdev);
 err_verify:
  pci_disable_device(pdev);
  return err;
@@ -108,6 +119,7 @@ static void remove(struct pci_dev *pdev)
  struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
 
  uio_unregister_device(&gdev->info);
+ pci_free_irq_vectors(pdev);
  pci_disable_device(pdev);
  kfree(gdev);
 }
-- 
2.11.0
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