[PATCH 2/2] drm/i915: add debugfs interface to control rc6 and rps

[Eugeni Dodonov <eugeni.dodonov@intel.com>]

This allows to enable/disable rps and rc6 from userspace. This is
necessary for to have predictable results from hardware counters, and also
to provide a finer granularity over power control from userspace.

As an additional trick, we also change the value of i915_enable_rc6 by
using this value, to allow the module to know the latest status of rc6
requested by user.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c  |  101 ++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 drivers/gpu/drm/i915/intel_drv.h     |    3 +
 3 files changed, 105 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 4f40f1c..dffc998 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1340,6 +1340,79 @@ static const struct file_operations i915_wedged_fops = {
 };
 
 static int
+i915_enable_rc6_open(struct inode *inode,
+		   struct file *filp)
+{
+	filp->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t
+i915_enable_rc6_read(struct file *filp,
+		   char __user *ubuf,
+		   size_t max,
+		   loff_t *ppos)
+{
+	char buf[80];
+	int len;
+
+	len = snprintf(buf, sizeof(buf),
+		       "%d\n", i915_enable_rc6);
+
+	if (len > sizeof(buf))
+		len = sizeof(buf);
+
+	return simple_read_from_buffer(ubuf, max, ppos, buf, len);
+}
+
+static ssize_t
+i915_enable_rc6_write(struct file *filp,
+		  const char __user *ubuf,
+		  size_t cnt,
+		  loff_t *ppos)
+{
+	struct drm_device *dev = filp->private_data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	char buf[20];
+	int val = -1;
+
+	if (cnt > 0) {
+		if (cnt > sizeof(buf) - 1)
+			return -EINVAL;
+
+		if (copy_from_user(buf, ubuf, cnt))
+			return -EFAULT;
+		buf[cnt] = 0;
+
+		val = simple_strtol(buf, NULL, 0);
+	}
+
+	if (INTEL_INFO(dev)->gen < 5)
+		return cnt;
+
+	DRM_DEBUG_DRIVER("Manually setting rps and rc6 status to %d\n", val);
+	i915_enable_rc6 = val;
+
+	if (val == 0) {
+		if (IS_IRONLAKE_M(dev))
+			ironlake_disable_rc6(dev);
+		else {
+			gen6_disable_rps(dev);
+			gen6_update_ring_freq(dev_priv);
+		}
+	} else {
+		if (IS_IRONLAKE_M(dev))
+			ironlake_disable_rc6(dev);
+		else {
+			gen6_enable_rps(dev_priv);
+			gen6_update_ring_freq(dev_priv);
+		}
+	}
+
+	return cnt;
+}
+
+static int
 i915_max_freq_open(struct inode *inode,
 		   struct file *filp)
 {
@@ -1401,6 +1474,14 @@ i915_max_freq_write(struct file *filp,
 	return cnt;
 }
 
+static const struct file_operations i915_enable_rc6_fops = {
+	.owner = THIS_MODULE,
+	.open = i915_enable_rc6_open,
+	.read = i915_enable_rc6_read,
+	.write = i915_enable_rc6_write,
+	.llseek = default_llseek,
+};
+
 static const struct file_operations i915_max_freq_fops = {
 	.owner = THIS_MODULE,
 	.open = i915_max_freq_open,
@@ -1605,6 +1686,21 @@ static int i915_max_freq_create(struct dentry *root, struct drm_minor *minor)
 	return drm_add_fake_info_node(minor, ent, &i915_max_freq_fops);
 }
 
+static int i915_enable_rc6_create(struct dentry *root, struct drm_minor *minor)
+{
+	struct drm_device *dev = minor->dev;
+	struct dentry *ent;
+
+	ent = debugfs_create_file("i915_enable_rc6",
+				  S_IRUGO | S_IWUSR,
+				  root, dev,
+				  &i915_enable_rc6_fops);
+	if (IS_ERR(ent))
+		return PTR_ERR(ent);
+
+	return drm_add_fake_info_node(minor, ent, &i915_enable_rc6_fops);
+}
+
 static int i915_cache_sharing_create(struct dentry *root, struct drm_minor *minor)
 {
 	struct drm_device *dev = minor->dev;
@@ -1676,6 +1772,9 @@ int i915_debugfs_init(struct drm_minor *minor)
 	ret = i915_max_freq_create(minor->debugfs_root, minor);
 	if (ret)
 		return ret;
+	ret = i915_enable_rc6_create(minor->debugfs_root, minor);
+	if (ret)
+		return ret;
 	ret = i915_cache_sharing_create(minor->debugfs_root, minor);
 	if (ret)
 		return ret;
@@ -1695,6 +1794,8 @@ void i915_debugfs_cleanup(struct drm_minor *minor)
 				 1, minor);
 	drm_debugfs_remove_files((struct drm_info_list *) &i915_max_freq_fops,
 				 1, minor);
+	drm_debugfs_remove_files((struct drm_info_list *) &i915_enable_rc6_fops,
+				 1, minor);
 	drm_debugfs_remove_files((struct drm_info_list *) &i915_cache_sharing_fops,
 				 1, minor);
 }
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d1e5726..cb15c8a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8311,7 +8311,7 @@ static void ironlake_teardown_rc6(struct drm_device *dev)
 	}
 }
 
-static void ironlake_disable_rc6(struct drm_device *dev)
+void ironlake_disable_rc6(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index bd9a604..ce11cc3 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -353,6 +353,9 @@ extern void gen6_update_ring_freq(struct drm_i915_private *dev_priv);
 extern void gen6_disable_rps(struct drm_device *dev);
 extern void intel_init_emon(struct drm_device *dev);
 
+extern void ironlake_enable_rc6(struct drm_device *dev);
+extern void ironlake_disable_rc6(struct drm_device *dev);
+
 extern int intel_pin_and_fence_fb_obj(struct drm_device *dev,
 				      struct drm_i915_gem_object *obj,
 				      struct intel_ring_buffer *pipelined);
-- 
1.7.7.4