drm/i915: protect RPS/RC6 related accesses (including PCU) with a new mutex

This allows the power related code to run independently of the rest of
the pipeline, extending the resume and init time improvements into
userspace, which would otherwise have been blocked on the struct mutex
if we were doing PCU communication.

v2: Also convert the locking for the rps sysfs interface.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 12 insertions, 25 deletions

diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index 9700ae96ec19..3bf51d58319d 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -211,12 +211,9 @@ static ssize_t gt_cur_freq_mhz_show(struct device *kdev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	ret = i915_mutex_lock_interruptible(dev);
-	if (ret)
-		return ret;
-
+	mutex_lock(&dev_priv->rps.hw_lock);
 	ret = dev_priv->rps.cur_delay * GT_FREQUENCY_MULTIPLIER;
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return snprintf(buf, PAGE_SIZE, "%d", ret);
 }
@@ -228,12 +225,9 @@ static ssize_t gt_max_freq_mhz_show(struct device *kdev, struct device_attribute
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	ret = i915_mutex_lock_interruptible(dev);
-	if (ret)
-		return ret;
-
+	mutex_lock(&dev_priv->rps.hw_lock);
 	ret = dev_priv->rps.max_delay * GT_FREQUENCY_MULTIPLIER;
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return snprintf(buf, PAGE_SIZE, "%d", ret);
 }
@@ -254,16 +248,14 @@ static ssize_t gt_max_freq_mhz_store(struct device *kdev,
 
 	val /= GT_FREQUENCY_MULTIPLIER;
 
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
+	mutex_lock(&dev_priv->rps.hw_lock);
 
 	rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
 	hw_max = (rp_state_cap & 0xff);
 	hw_min = ((rp_state_cap & 0xff0000) >> 16);
 
 	if (val < hw_min || val > hw_max || val < dev_priv->rps.min_delay) {
-		mutex_unlock(&dev->struct_mutex);
+		mutex_unlock(&dev_priv->rps.hw_lock);
 		return -EINVAL;
 	}
 
@@ -272,7 +264,7 @@ static ssize_t gt_max_freq_mhz_store(struct device *kdev,
 
 	dev_priv->rps.max_delay = val;
 
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return count;
 }
@@ -284,12 +276,9 @@ static ssize_t gt_min_freq_mhz_show(struct device *kdev, struct device_attribute
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
-	ret = i915_mutex_lock_interruptible(dev);
-	if (ret)
-		return ret;
-
+	mutex_lock(&dev_priv->rps.hw_lock);
 	ret = dev_priv->rps.min_delay * GT_FREQUENCY_MULTIPLIER;
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return snprintf(buf, PAGE_SIZE, "%d", ret);
 }
@@ -310,16 +299,14 @@ static ssize_t gt_min_freq_mhz_store(struct device *kdev,
 
 	val /= GT_FREQUENCY_MULTIPLIER;
 
-	ret = mutex_lock_interruptible(&dev->struct_mutex);
-	if (ret)
-		return ret;
+	mutex_lock(&dev_priv->rps.hw_lock);
 
 	rp_state_cap = I915_READ(GEN6_RP_STATE_CAP);
 	hw_max = (rp_state_cap & 0xff);
 	hw_min = ((rp_state_cap & 0xff0000) >> 16);
 
 	if (val < hw_min || val > hw_max || val > dev_priv->rps.max_delay) {
-		mutex_unlock(&dev->struct_mutex);
+		mutex_unlock(&dev_priv->rps.hw_lock);
 		return -EINVAL;
 	}
 
@@ -328,7 +315,7 @@ static ssize_t gt_min_freq_mhz_store(struct device *kdev,
 
 	dev_priv->rps.min_delay = val;
 
-	mutex_unlock(&dev->struct_mutex);
+	mutex_unlock(&dev_priv->rps.hw_lock);
 
 	return count;