This patch will likely produce much fewer warnings, but perhaps hide
some bugs in the driver. I believe it's a good starting point however to
find the really serious issues first.
Goal is to hide warnings if the refcount for the forcewake "lock" is not
zero
Signed-off-by: Ben Widawsky <b...@bwidawsk.net>
---
drivers/gpu/drm/i915/i915_drv.c | 14 ++++++++++----
1 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index fcd5c9a..33341d4 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -286,9 +286,14 @@ void gen6_gt_force_wake_get(struct drm_i915_private
*dev_priv)
* immediately. Not having the lock causes a race, but all bets are off
* when using forced forcewake, which should only be touched through
* root-only entry in debugfs.
+ *
+ * Intelligent users of the interface may do a force_wake_get() followed
+ * by many register reads and writes, knowing that the reference count
+ * is already incremented. So we do not want to warn on those.
*/
- WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex) &&
- !atomic_read(&dev_priv->forcewake_force));
+ WARN_ON((!mutex_is_locked(&dev_priv->dev->struct_mutex) &&
+ !dev_priv->forcewake_count) &&
+ !atomic_read(&dev_priv->forcewake_force));
if (dev_priv->forcewake_count++ == 0)
__gen6_gt_force_wake_get(dev_priv);
@@ -302,8 +307,9 @@ 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) &&
- !atomic_read(&dev_priv->forcewake_force));
+ WARN_ON((!mutex_is_locked(&dev_priv->dev->struct_mutex) &&
+ !dev_priv->forcewake_count) &&
+ !atomic_read(&dev_priv->forcewake_force));
if (--dev_priv->forcewake_count == 0)
__gen6_gt_force_wake_put(dev_priv);
--
1.7.3.4
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