[Intel-gfx] [PATCH] drm/i915: protect force_wake_(get|put) with the gt_lock
Daniel Vetter
daniel.vetter at ffwll.ch
Sun Nov 6 12:31:34 CET 2011
We don't have any read in a fastpath that needs forcewake, so I've
decided to not care much about overhead.
This prevents tests/gem_hangcheck_forcewake from i-g-t from killing my
snb on recent kernels - something must have slightly changed the
timings.
v2: Drop the previous patch for the register writes.
Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/gpu/drm/i915/i915_debugfs.c | 8 ++++++--
drivers/gpu/drm/i915/i915_dma.c | 1 +
drivers/gpu/drm/i915/i915_drv.c | 19 +++++++++++++------
drivers/gpu/drm/i915/i915_drv.h | 10 +++++++---
4 files changed, 27 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5ba63ad..51b21eb 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1320,9 +1320,13 @@ static int i915_gen6_forcewake_count_info(struct seq_file *m, void *data)
struct drm_info_node *node = (struct drm_info_node *) m->private;
struct drm_device *dev = node->minor->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
+ unsigned forcewake_count;
- seq_printf(m, "forcewake count = %d\n",
- atomic_read(&dev_priv->forcewake_count));
+ spin_lock_irq(&dev_priv->gt_lock);
+ forcewake_count = dev_priv->forcewake_count;
+ spin_unlock_irq(&dev_priv->gt_lock);
+
+ seq_printf(m, "forcewake count = %d\n", forcewake_count);
return 0;
}
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 2eac955..ab3a3fd 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -2031,6 +2031,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
if (!IS_I945G(dev) && !IS_I945GM(dev))
pci_enable_msi(dev->pdev);
+ spin_lock_init(&dev_priv->gt_lock);
spin_lock_init(&dev_priv->irq_lock);
spin_lock_init(&dev_priv->error_lock);
spin_lock_init(&dev_priv->rps_lock);
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 548e04b..bab4e08 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -351,11 +351,12 @@ 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 irqflags;
- /* 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->gt_lock, irqflags);
+ if (dev_priv->forcewake_count++ == 0)
__gen6_gt_force_wake_get(dev_priv);
+ spin_unlock_irqrestore(&dev_priv->gt_lock, irqflags);
}
static void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
@@ -369,10 +370,13 @@ 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 irqflags;
- if (atomic_dec_and_test(&dev_priv->forcewake_count))
+ spin_lock_irqsave(&dev_priv->gt_lock, irqflags);
+
+ if (--dev_priv->forcewake_count == 0)
__gen6_gt_force_wake_put(dev_priv);
+ spin_unlock_irqrestore(&dev_priv->gt_lock, irqflags);
}
void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
@@ -603,6 +607,7 @@ int i915_reset(struct drm_device *dev, u8 flags)
* need to
*/
bool need_display = true;
+ unsigned long irqflags;
int ret;
if (!i915_try_reset)
@@ -621,8 +626,10 @@ int i915_reset(struct drm_device *dev, u8 flags)
case 6:
ret = gen6_do_reset(dev, flags);
/* If reset with a user forcewake, try to restore */
- if (atomic_read(&dev_priv->forcewake_count))
+ spin_lock_irqsave(&dev_priv->gt_lock, irqflags);
+ if (dev_priv->forcewake_count)
__gen6_gt_force_wake_get(dev_priv);
+ spin_unlock_irqrestore(&dev_priv->gt_lock, irqflags);
break;
case 5:
ret = ironlake_do_reset(dev, flags);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index bd98fb3..25036f5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -276,7 +276,13 @@ typedef struct drm_i915_private {
int relative_constants_mode;
void __iomem *regs;
- u32 gt_fifo_count;
+ /** gt_fifo_count and the subsequent register write are synchronized
+ * with dev->struct_mutex. */
+ unsigned gt_fifo_count;
+ /** forcewake_count is protected by gt_lock */
+ unsigned forcewake_count;
+ /** gt_lock is also taken in irq contexts. */
+ struct spinlock gt_lock;
struct intel_gmbus {
struct i2c_adapter adapter;
@@ -725,8 +731,6 @@ typedef struct drm_i915_private {
struct drm_property *broadcast_rgb_property;
struct drm_property *force_audio_property;
-
- atomic_t forcewake_count;
} drm_i915_private_t;
enum i915_cache_level {
--
1.7.6.4
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