drm/i915: Use a global lock for modifying global irq flags

We were attempting to use a per-ring spinlock whilst modifying global
IRQ flags. A recipe for rare missed interrupts.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index f797613..b7f446e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -610,17 +610,18 @@ gen5_ring_get_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
        if (!dev->irq_enabled)
                return false;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                dev_priv->gt_irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE(GTIMR, dev_priv->gt_irq_mask);
                POSTING_READ(GTIMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
        return true;
 }
@@ -630,14 +631,15 @@ gen5_ring_put_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                dev_priv->gt_irq_mask |= ring->irq_enable_mask;
                I915_WRITE(GTIMR, dev_priv->gt_irq_mask);
                POSTING_READ(GTIMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 }
 
 static bool
@@ -645,17 +647,18 @@ i9xx_ring_get_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
        if (!dev->irq_enabled)
                return false;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                dev_priv->irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE(IMR, dev_priv->irq_mask);
                POSTING_READ(IMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
        return true;
 }
@@ -665,14 +668,15 @@ i9xx_ring_put_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                dev_priv->irq_mask |= ring->irq_enable_mask;
                I915_WRITE(IMR, dev_priv->irq_mask);
                POSTING_READ(IMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 }
 
 static bool
@@ -680,17 +684,18 @@ i8xx_ring_get_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
        if (!dev->irq_enabled)
                return false;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                dev_priv->irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE16(IMR, dev_priv->irq_mask);
                POSTING_READ16(IMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
        return true;
 }
@@ -700,14 +705,15 @@ i8xx_ring_put_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                dev_priv->irq_mask |= ring->irq_enable_mask;
                I915_WRITE16(IMR, dev_priv->irq_mask);
                POSTING_READ16(IMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 }
 
 void intel_ring_setup_status_page(struct intel_ring_buffer *ring)
@@ -786,6 +792,7 @@ gen6_ring_get_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
        if (!dev->irq_enabled)
               return false;
@@ -795,14 +802,14 @@ gen6_ring_get_irq(struct intel_ring_buffer *ring)
         * blt/bsd rings on ivb. */
        gen6_gt_force_wake_get(dev_priv);
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (ring->irq_refcount++ == 0) {
                I915_WRITE_IMR(ring, ~ring->irq_enable_mask);
                dev_priv->gt_irq_mask &= ~ring->irq_enable_mask;
                I915_WRITE(GTIMR, dev_priv->gt_irq_mask);
                POSTING_READ(GTIMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
        return true;
 }
@@ -812,15 +819,16 @@ gen6_ring_put_irq(struct intel_ring_buffer *ring)
 {
        struct drm_device *dev = ring->dev;
        drm_i915_private_t *dev_priv = dev->dev_private;
+       unsigned long flags;
 
-       spin_lock(&ring->irq_lock);
+       spin_lock_irqsave(&dev_priv->irq_lock, flags);
        if (--ring->irq_refcount == 0) {
                I915_WRITE_IMR(ring, ~0);
                dev_priv->gt_irq_mask |= ring->irq_enable_mask;
                I915_WRITE(GTIMR, dev_priv->gt_irq_mask);
                POSTING_READ(GTIMR);
        }
-       spin_unlock(&ring->irq_lock);
+       spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 
        gen6_gt_force_wake_put(dev_priv);
 }
@@ -954,7 +962,6 @@ static int intel_init_ring_buffer(struct drm_device *dev,
        ring->size = 32 * PAGE_SIZE;
 
        init_waitqueue_head(&ring->irq_queue);
-       spin_lock_init(&ring->irq_lock);
 
        if (I915_NEED_GFX_HWS(dev)) {
                ret = init_status_page(ring);

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 06a66ad..e0b25bb 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -56,8 +56,7 @@ struct  intel_ring_buffer {
         */
        u32             last_retired_head;
 
-       spinlock_t      irq_lock;
-       u32             irq_refcount;
+       u32             irq_refcount;           /* protected by dev_priv->irq_lock */
        u32             irq_enable_mask;        /* bitmask to enable ring interrupt */
        u32             irq_seqno;              /* last seq seem at irq time */
        u32             trace_irq_seqno;