gpu: nvgpu: enable PCI MSI interrupts

Use MSI interrupts instead of legacy on PCIe
dGPUs to reduce latency and contention with other
PCIe devices

JIRA EVLR-986

Change-Id: I6cecc7e62e5797860d42a5bee21e8f4f664e1b18
Signed-off-by: David Nieto <dmartineznie@nvidia.com>
Reviewed-on: http://git-master/r/1291758
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/pci.c b/drivers/gpu/nvgpu/pci.c
index feb253b6..648fc60e 100644
--- a/drivers/gpu/nvgpu/pci.c
+++ b/drivers/gpu/nvgpu/pci.c
@@ -226,6 +226,12 @@ static irqreturn_t nvgpu_pci_isr(int irq, void *dev_id)
         ret_stall = g->ops.mc.isr_stall(g);
         ret_nonstall = g->ops.mc.isr_nonstall(g);
 
+#if defined(CONFIG_PCI_MSI)
+        /* Send MSI EOI */
+        if (g->ops.xve.rearm_msi && g->msi_enabled)
+                g->ops.xve.rearm_msi(g);
+#endif
+
         return (ret_stall == IRQ_NONE && ret_nonstall == IRQ_NONE) ?
                 IRQ_NONE : IRQ_WAKE_THREAD;
 }
@@ -361,6 +367,16 @@ static int nvgpu_pci_probe(struct pci_dev *pdev,
         g->pci_class = (pdev->class >> 8) & 0xFFFFU; // we only want base/sub
         g->pci_revision = pdev->revision;
 
+#if defined(CONFIG_PCI_MSI)
+        err = pci_enable_msi(pdev);
+        if (err) {
+                gk20a_err(&pdev->dev,
+                        "MSI could not be enabled, falling back to legacy");
+                g->msi_enabled = false;
+        } else
+                g->msi_enabled = true;
+#endif
+
         g->irq_stall = pdev->irq;
         g->irq_nonstall = pdev->irq;
         if (g->irq_stall < 0)
@@ -370,6 +386,9 @@ static int nvgpu_pci_probe(struct pci_dev *pdev,
                         g->irq_stall,
                         nvgpu_pci_isr,
                         nvgpu_pci_intr_thread,
+#if defined(CONFIG_PCI_MSI)
+                        g->msi_enabled ? 0 :
+#endif
                         IRQF_SHARED, "nvgpu", g);
         if (err) {
                 gk20a_err(&pdev->dev,
@@ -419,6 +438,13 @@ static void nvgpu_pci_remove(struct pci_dev *pdev)
 
         disable_irq(g->irq_stall);
         devm_free_irq(&pdev->dev, g->irq_stall, g);
+
+#if defined(CONFIG_PCI_MSI)
+        if (g->msi_enabled) {
+                pci_disable_msi(pdev);
+                g->msi_enabled = false;
+        }
+#endif
         gk20a_dbg(gpu_dbg_shutdown, "IRQs disabled.\n");
 
         /*