We have forcewake in the interrupt handler in the following commit, so
we have to use a spinlock instead of a mutex.

Signed-off-by: Eric Anholt <[email protected]>
---
 drivers/gpu/drm/i915/i915_debugfs.c |    3 +--
 drivers/gpu/drm/i915/i915_dma.c     |    1 +
 drivers/gpu/drm/i915/i915_drv.c     |   17 ++++++++++++-----
 drivers/gpu/drm/i915/i915_drv.h     |    3 ++-
 4 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index 51c2257..e62ee5d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1226,8 +1226,7 @@ static int i915_gen6_forcewake_count_info(struct seq_file 
*m, void *data)
        struct drm_device *dev = node->minor->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
 
-       seq_printf(m, "forcewake count = %d\n",
-                  atomic_read(&dev_priv->forcewake_count));
+       seq_printf(m, "forcewake count = %d\n", dev_priv->forcewake_count);
 
        return 0;
 }
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 0239e99..2de4a74 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -2063,6 +2063,7 @@ int i915_driver_load(struct drm_device *dev, unsigned 
long flags)
        spin_lock_init(&dev_priv->irq_lock);
        spin_lock_init(&dev_priv->error_lock);
        spin_lock_init(&dev_priv->rps_lock);
+       spin_lock_init(&dev_priv->forcewake_lock);
 
        if (IS_MOBILE(dev) || !IS_GEN2(dev))
                dev_priv->num_pipe = 2;
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 0defd42..0c46bfc 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -319,11 +319,14 @@ static void __gen6_gt_force_wake_get(struct 
drm_i915_private *dev_priv)
  */
 void gen6_gt_force_wake_get(struct drm_i915_private *dev_priv)
 {
-       WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+       unsigned long flags;
 
-       /* Forcewake is atomic in case we get in here without the lock */
-       if (atomic_add_return(1, &dev_priv->forcewake_count) == 1)
+       spin_lock_irqsave(&dev_priv->forcewake_lock, flags);
+
+       if (dev_priv->forcewake_count++ == 0)
                __gen6_gt_force_wake_get(dev_priv);
+
+       spin_unlock_irqrestore(&dev_priv->forcewake_lock, flags);
 }
 
 static void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
@@ -337,10 +340,14 @@ static void __gen6_gt_force_wake_put(struct 
drm_i915_private *dev_priv)
  */
 void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
 {
-       WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+       unsigned long flags;
 
-       if (atomic_dec_and_test(&dev_priv->forcewake_count))
+       spin_lock_irqsave(&dev_priv->forcewake_lock, flags);
+
+       if (--dev_priv->forcewake_count == 0)
                __gen6_gt_force_wake_put(dev_priv);
+
+       spin_unlock_irqrestore(&dev_priv->forcewake_lock, flags);
 }
 
 void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ee66035..56ef324 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -717,7 +717,8 @@ typedef struct drm_i915_private {
 
        struct drm_property *broadcast_rgb_property;
 
-       atomic_t forcewake_count;
+       int forcewake_count;
+       spinlock_t forcewake_lock;
 } drm_i915_private_t;
 
 enum i915_cache_level {
-- 
1.7.5.1

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