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drm/i915: debugfs interface for forcewake reference count

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forcewake is controlled by the open and close of the debugfs file. This
assures that buggy applications cannot cause the GT to stay on forever.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Ben Widawsky 2011-04-25 11:25:56 -07:00 committed by Keith Packard
parent 4912d04193
commit 6d794d4250
1 changed files with 80 additions and 0 deletions
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80
drivers/gpu/drm/i915/i915_debugfs.c
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@ -1217,6 +1217,18 @@ static int i915_context_status(struct seq_file *m, void *unused)
return 0;
}
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;
seq_printf(m, "forcewake count = %d\n",
atomic_read(&dev_priv->forcewake_count));
return 0;
}
static int
i915_wedged_open(struct inode *inode,
struct file *filp)
@ -1319,6 +1331,67 @@ static int i915_wedged_create(struct dentry *root, struct drm_minor *minor)
return drm_add_fake_info_node(minor, ent, &i915_wedged_fops);
}
static int i915_forcewake_open(struct inode *inode, struct file *file)
{
struct drm_device *dev = inode->i_private;
struct drm_i915_private *dev_priv = dev->dev_private;
int ret;
if (!IS_GEN6(dev))
return 0;
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
gen6_gt_force_wake_get(dev_priv);
mutex_unlock(&dev->struct_mutex);
return 0;
}
int i915_forcewake_release(struct inode *inode, struct file *file)
{
struct drm_device *dev = inode->i_private;
struct drm_i915_private *dev_priv = dev->dev_private;
if (!IS_GEN6(dev))
return 0;
/*
* It's bad that we can potentially hang userspace if struct_mutex gets
* forever stuck. However, if we cannot acquire this lock it means that
* almost certainly the driver has hung, is not unload-able. Therefore
* hanging here is probably a minor inconvenience not to be seen my
* almost every user.
*/
mutex_lock(&dev->struct_mutex);
gen6_gt_force_wake_put(dev_priv);
mutex_unlock(&dev->struct_mutex);
return 0;
}
static const struct file_operations i915_forcewake_fops = {
.owner = THIS_MODULE,
.open = i915_forcewake_open,
.release = i915_forcewake_release,
};
static int i915_forcewake_create(struct dentry *root, struct drm_minor *minor)
{
struct drm_device *dev = minor->dev;
struct dentry *ent;
ent = debugfs_create_file("i915_forcewake_user",
S_IRWXU,
root, dev,
&i915_forcewake_fops);
if (IS_ERR(ent))
return PTR_ERR(ent);
return 0;
}
static struct drm_info_list i915_debugfs_list[] = {
{"i915_capabilities", i915_capabilities, 0},
{"i915_gem_objects", i915_gem_object_info, 0},
@ -1356,6 +1429,7 @@ static struct drm_info_list i915_debugfs_list[] = {
{"i915_opregion", i915_opregion, 0},
{"i915_gem_framebuffer", i915_gem_framebuffer_info, 0},
{"i915_context_status", i915_context_status, 0},
{"i915_gen6_forcewake_count", i915_gen6_forcewake_count_info, 0},
};
#define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)
@ -1367,6 +1441,10 @@ int i915_debugfs_init(struct drm_minor *minor)
if (ret)
return ret;
ret = i915_forcewake_create(minor->debugfs_root, minor);
if (ret)
return ret;
return drm_debugfs_create_files(i915_debugfs_list,
I915_DEBUGFS_ENTRIES,
minor->debugfs_root, minor);
@ -1376,6 +1454,8 @@ void i915_debugfs_cleanup(struct drm_minor *minor)
{
drm_debugfs_remove_files(i915_debugfs_list,
I915_DEBUGFS_ENTRIES, minor);
drm_debugfs_remove_files((struct drm_info_list *) &i915_forcewake_fops,
1, minor);
drm_debugfs_remove_files((struct drm_info_list *) &i915_wedged_fops,
1, minor);
}