drm/i915/bdw: Handle context switch events

Handle all context status events in the context status buffer on every
context switch interrupt. We only remove work from the execlist queue
after a context status buffer reports that it has completed and we only
attempt to schedule new contexts on interrupt when a previously submitted
context completes (unless no contexts are queued, which means the GPU is
free).

We canot call intel_runtime_pm_get() in an interrupt (or with a spinlock
grabbed, FWIW), because it might sleep, which is not a nice thing to do.
Instead, do the runtime_pm get/put together with the create/destroy request,
and handle the forcewake get/put directly.

Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>

v2: Unreferencing the context when we are freeing the request might free
the backing bo, which requires the struct_mutex to be grabbed, so defer
unreferencing and freeing to a bottom half.

v3:
- Ack the interrupt inmediately, before trying to handle it (fix for
missing interrupts by Bob Beckett <robert.beckett@intel.com>).
- Update the Context Status Buffer Read Pointer, just in case (spotted
by Damien Lespiau).

v4: New namespace and multiple rebase changes.

v5: Squash with "drm/i915/bdw: Do not call intel_runtime_pm_get() in an
interrupt", as suggested by Daniel.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
[danvet: Checkpatch ...]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 24 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 00957fa0b877..f5d6795887d2 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1632,6 +1632,7 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
                                        struct drm_i915_private *dev_priv,
                                        u32 master_ctl)
 {
+        struct intel_engine_cs *ring;
         u32 rcs, bcs, vcs;
         uint32_t tmp = 0;
         irqreturn_t ret = IRQ_NONE;
@@ -1641,14 +1642,20 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
                 if (tmp) {
                         I915_WRITE(GEN8_GT_IIR(0), tmp);
                         ret = IRQ_HANDLED;
+
                         rcs = tmp >> GEN8_RCS_IRQ_SHIFT;
-                        bcs = tmp >> GEN8_BCS_IRQ_SHIFT;
+                        ring = &dev_priv->ring[RCS];
                         if (rcs & GT_RENDER_USER_INTERRUPT)
-                                notify_ring(dev, &dev_priv->ring[RCS]);
+                                notify_ring(dev, ring);
+                        if (rcs & GT_CONTEXT_SWITCH_INTERRUPT)
+                                intel_execlists_handle_ctx_events(ring);
+
+                        bcs = tmp >> GEN8_BCS_IRQ_SHIFT;
+                        ring = &dev_priv->ring[BCS];
                         if (bcs & GT_RENDER_USER_INTERRUPT)
-                                notify_ring(dev, &dev_priv->ring[BCS]);
-                        if ((rcs | bcs) & GT_CONTEXT_SWITCH_INTERRUPT)
-                                DRM_DEBUG_DRIVER("TODO: Context switch\n");
+                                notify_ring(dev, ring);
+                        if (bcs & GT_CONTEXT_SWITCH_INTERRUPT)
+                                intel_execlists_handle_ctx_events(ring);
                 } else
                         DRM_ERROR("The master control interrupt lied (GT0)!\n");
         }
@@ -1658,16 +1665,20 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
                 if (tmp) {
                         I915_WRITE(GEN8_GT_IIR(1), tmp);
                         ret = IRQ_HANDLED;
+
                         vcs = tmp >> GEN8_VCS1_IRQ_SHIFT;
+                        ring = &dev_priv->ring[VCS];
                         if (vcs & GT_RENDER_USER_INTERRUPT)
-                                notify_ring(dev, &dev_priv->ring[VCS]);
+                                notify_ring(dev, ring);
                         if (vcs & GT_CONTEXT_SWITCH_INTERRUPT)
-                                DRM_DEBUG_DRIVER("TODO: Context switch\n");
+                                intel_execlists_handle_ctx_events(ring);
+
                         vcs = tmp >> GEN8_VCS2_IRQ_SHIFT;
+                        ring = &dev_priv->ring[VCS2];
                         if (vcs & GT_RENDER_USER_INTERRUPT)
-                                notify_ring(dev, &dev_priv->ring[VCS2]);
+                                notify_ring(dev, ring);
                         if (vcs & GT_CONTEXT_SWITCH_INTERRUPT)
-                                DRM_DEBUG_DRIVER("TODO: Context switch\n");
+                                intel_execlists_handle_ctx_events(ring);
                 } else
                         DRM_ERROR("The master control interrupt lied (GT1)!\n");
         }
@@ -1688,11 +1699,13 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_device *dev,
                 if (tmp) {
                         I915_WRITE(GEN8_GT_IIR(3), tmp);
                         ret = IRQ_HANDLED;
+
                         vcs = tmp >> GEN8_VECS_IRQ_SHIFT;
+                        ring = &dev_priv->ring[VECS];
                         if (vcs & GT_RENDER_USER_INTERRUPT)
-                                notify_ring(dev, &dev_priv->ring[VECS]);
+                                notify_ring(dev, ring);
                         if (vcs & GT_CONTEXT_SWITCH_INTERRUPT)
-                                DRM_DEBUG_DRIVER("TODO: Context switch\n");
+                                intel_execlists_handle_ctx_events(ring);
                 } else
                         DRM_ERROR("The master control interrupt lied (GT3)!\n");
         }