Re: [PATCH 2/2] uio: Prefer MSI(X) interrupts in PCI drivers
From: Stahl, Manuel
Date: Fri Oct 06 2017 - 09:50:51 EST
MSI(X) interrupts are not shared between devices. So when available
those should be preferred over legacy interrupts.
Signed-off-by: Manuel Stahl <manuel.stahl@xxxxxxxxxxxxxxxxx>
---
Âdrivers/uio/uio_pci_dmem_genirq.c | 27 ++++++++++++++++++++-------
Âdrivers/uio/uio_pci_generic.cÂÂÂÂÂ| 24 ++++++++++++++++++------
Â2 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)
Â{
 struct uio_pci_dmem_dev *gdev = to_uio_pci_dmem_dev(info);
Â
- if (!pci_check_and_mask_intx(gdev->pdev))
- return IRQ_NONE;
+ if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+ return IRQ_HANDLED;
Â
- /* UIO core will signal the user process. */
- return IRQ_HANDLED;
+ if (pci_check_and_mask_intx(gdev->pdev))
+ return IRQ_HANDLED;
+
+ return IRQ_NONE;
Â}
Â
Âstatic 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);
Â
- 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 &&
+ ÂÂÂÂ!pci_intx_mask_supported(pdev)) {
+ err = -ENODEV;
+ goto err_free_irq_vectors;
+ }
+ dev_info(&pdev->dev, "IRQ: %i", pdev->irq);
Â
 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;
Âerr_free_gdev:
 kfree(gdev);
+err_free_irq_vectors:
+ pci_free_irq_vectors(pdev);
Âerr_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);
Â
 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)
Â{
 struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
Â
- if (!pci_check_and_mask_intx(gdev->pdev))
- return IRQ_NONE;
+ if (gdev->pdev->msi_enabled || gdev->pdev->msix_enabled)
+ return IRQ_HANDLED;
Â
- /* UIO core will signal the user process. */
- return IRQ_HANDLED;
+ if (pci_check_and_mask_intx(gdev->pdev))
+ return IRQ_HANDLED;
+
+ return IRQ_NONE;
Â}
Â
Âstatic int probe(struct pci_dev *pdev,
@@ -66,10 +68,18 @@ static int probe(struct pci_dev *pdev,
 return err;
 }
Â
- 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 &&
+ ÂÂÂÂ!pci_intx_mask_supported(pdev)) {
+ err = -ENODEV;
+ goto err_alloc;
+ }
Â
 gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
 if (!gdev) {
@@ -98,6 +108,7 @@ static int probe(struct pci_dev *pdev,
Âerr_register:
 kfree(gdev);
Âerr_alloc:
+ pci_free_irq_vectors(pdev);
Âerr_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);
Â
 uio_unregister_device(&gdev->info);
+ pci_free_irq_vectors(pdev);
 pci_disable_device(pdev);
 kfree(gdev);
Â}
--Â
2.11.0