i915: Add support for MSI and interrupt mitigation.

Previous attempts at interrupt mitigation had been foiled by i915_wait_irq's
failure to update the sarea seqno value when the status page indicated that
the seqno had already been passed.  MSI support has been seen to cut CPU
costs by up to 40% in some workloads by avoiding other expensive interrupt
handlers for frequent graphics interrupts.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 12 insertions, 8 deletions

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 53f0e5af1cc8..61ed5158f783 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -63,7 +63,7 @@ int drm_irq_by_busid(struct drm_device *dev, void *data,
             p->devnum != PCI_SLOT(dev->pdev->devfn) || p->funcnum != PCI_FUNC(dev->pdev->devfn))
                 return -EINVAL;
 
-        p->irq = dev->irq;
+        p->irq = dev->pdev->irq;
 
         DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
                   p->irq);
@@ -89,7 +89,7 @@ static int drm_irq_install(struct drm_device * dev)
         if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
                 return -EINVAL;
 
-        if (dev->irq == 0)
+        if (dev->pdev->irq == 0)
                 return -EINVAL;
 
         mutex_lock(&dev->struct_mutex);
@@ -107,7 +107,7 @@ static int drm_irq_install(struct drm_device * dev)
         dev->irq_enabled = 1;
         mutex_unlock(&dev->struct_mutex);
 
-        DRM_DEBUG("irq=%d\n", dev->irq);
+        DRM_DEBUG("irq=%d\n", dev->pdev->irq);
 
         if (drm_core_check_feature(dev, DRIVER_IRQ_VBL)) {
                 init_waitqueue_head(&dev->vbl_queue);
@@ -127,8 +127,12 @@ static int drm_irq_install(struct drm_device * dev)
         if (drm_core_check_feature(dev, DRIVER_IRQ_SHARED))
                 sh_flags = IRQF_SHARED;
 
-        ret = request_irq(dev->irq, dev->driver->irq_handler,
+        ret = request_irq(dev->pdev->irq, dev->driver->irq_handler,
                           sh_flags, dev->devname, dev);
+        /* Expose the device irq number to drivers that want to export it for
+         * whatever reason.
+         */
+        dev->irq = dev->pdev->irq;
         if (ret < 0) {
                 mutex_lock(&dev->struct_mutex);
                 dev->irq_enabled = 0;
@@ -164,11 +168,11 @@ int drm_irq_uninstall(struct drm_device * dev)
         if (!irq_enabled)
                 return -EINVAL;
 
-        DRM_DEBUG("irq=%d\n", dev->irq);
+        DRM_DEBUG("irq=%d\n", dev->pdev->irq);
 
         dev->driver->irq_uninstall(dev);
 
-        free_irq(dev->irq, dev);
+        free_irq(dev->pdev->irq, dev);
 
         dev->locked_tasklet_func = NULL;
 
@@ -201,7 +205,7 @@ int drm_control(struct drm_device *dev, void *data,
                 if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
                         return 0;
                 if (dev->if_version < DRM_IF_VERSION(1, 2) &&
-                    ctl->irq != dev->irq)
+                    ctl->irq != dev->pdev->irq)
                         return -EINVAL;
                 return drm_irq_install(dev);
         case DRM_UNINST_HANDLER:
@@ -239,7 +243,7 @@ int drm_wait_vblank(struct drm_device *dev, void *data, struct drm_file *file_pr
         int ret = 0;
         unsigned int flags, seq;
 
-        if ((!dev->irq) || (!dev->irq_enabled))
+        if ((!dev->pdev->irq) || (!dev->irq_enabled))
                 return -EINVAL;
 
         if (vblwait->request.type &