drm/i915: Define a separate variable and control for RPS waitboost frequency

To allow the user finer control over waitboosting, allow them to set the
frequency we request for the boost. This also them allows to effectively
disable the boosting by setting the boost request to a low frequency.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1468397438-21226-5-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index d61829e..8c045ff 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -318,6 +318,41 @@
 	return snprintf(buf, PAGE_SIZE, "%d\n", ret);
 }
 
+static ssize_t gt_boost_freq_mhz_show(struct device *kdev, struct device_attribute *attr, char *buf)
+{
+	struct drm_minor *minor = dev_to_drm_minor(kdev);
+	struct drm_i915_private *dev_priv = to_i915(minor->dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			intel_gpu_freq(dev_priv, dev_priv->rps.boost_freq));
+}
+
+static ssize_t gt_boost_freq_mhz_store(struct device *kdev,
+				       struct device_attribute *attr,
+				       const char *buf, size_t count)
+{
+	struct drm_minor *minor = dev_to_drm_minor(kdev);
+	struct drm_device *dev = minor->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	u32 val;
+	ssize_t ret;
+
+	ret = kstrtou32(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	/* Validate against (static) hardware limits */
+	val = intel_freq_opcode(dev_priv, val);
+	if (val < dev_priv->rps.min_freq || val > dev_priv->rps.max_freq)
+		return -EINVAL;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	dev_priv->rps.boost_freq = val;
+	mutex_unlock(&dev_priv->rps.hw_lock);
+
+	return count;
+}
+
 static ssize_t vlv_rpe_freq_mhz_show(struct device *kdev,
 				     struct device_attribute *attr, char *buf)
 {
@@ -465,6 +500,7 @@
 
 static DEVICE_ATTR(gt_act_freq_mhz, S_IRUGO, gt_act_freq_mhz_show, NULL);
 static DEVICE_ATTR(gt_cur_freq_mhz, S_IRUGO, gt_cur_freq_mhz_show, NULL);
+static DEVICE_ATTR(gt_boost_freq_mhz, S_IRUGO, gt_boost_freq_mhz_show, gt_boost_freq_mhz_store);
 static DEVICE_ATTR(gt_max_freq_mhz, S_IRUGO | S_IWUSR, gt_max_freq_mhz_show, gt_max_freq_mhz_store);
 static DEVICE_ATTR(gt_min_freq_mhz, S_IRUGO | S_IWUSR, gt_min_freq_mhz_show, gt_min_freq_mhz_store);
 
@@ -498,6 +534,7 @@
 static const struct attribute *gen6_attrs[] = {
 	&dev_attr_gt_act_freq_mhz.attr,
 	&dev_attr_gt_cur_freq_mhz.attr,
+	&dev_attr_gt_boost_freq_mhz.attr,
 	&dev_attr_gt_max_freq_mhz.attr,
 	&dev_attr_gt_min_freq_mhz.attr,
 	&dev_attr_gt_RP0_freq_mhz.attr,
@@ -509,6 +546,7 @@
 static const struct attribute *vlv_attrs[] = {
 	&dev_attr_gt_act_freq_mhz.attr,
 	&dev_attr_gt_cur_freq_mhz.attr,
+	&dev_attr_gt_boost_freq_mhz.attr,
 	&dev_attr_gt_max_freq_mhz.attr,
 	&dev_attr_gt_min_freq_mhz.attr,
 	&dev_attr_gt_RP0_freq_mhz.attr,