drm/i915: add min freq control to debugfs

This makes for easier benchmarking and testing.  One can set a fixed
frequency by setting min and max to the same value.

v2: fix whitespace & comment (Eugeni)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Eugeni Dodonov <eugeni@dodonov.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5363e9c..4fa00fc 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1765,6 +1765,64 @@ static const struct file_operations i915_max_freq_fops = {
 };
 
 static ssize_t
+i915_min_freq_read(struct file *filp, char __user *ubuf, size_t max,
+                  loff_t *ppos)
+{
+       struct drm_device *dev = filp->private_data;
+       drm_i915_private_t *dev_priv = dev->dev_private;
+       char buf[80];
+       int len;
+
+       len = snprintf(buf, sizeof(buf),
+                      "min freq: %d\n", dev_priv->min_delay * 50);
+
+       if (len > sizeof(buf))
+               len = sizeof(buf);
+
+       return simple_read_from_buffer(ubuf, max, ppos, buf, len);
+}
+
+static ssize_t
+i915_min_freq_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_strtoul(buf, NULL, 0);
+       }
+
+       DRM_DEBUG_DRIVER("Manually setting min freq to %d\n", val);
+
+       /*
+        * Turbo will still be enabled, but won't go below the set value.
+        */
+       dev_priv->min_delay = val / 50;
+
+       gen6_set_rps(dev, val / 50);
+
+       return cnt;
+}
+
+static const struct file_operations i915_min_freq_fops = {
+       .owner = THIS_MODULE,
+       .open = simple_open,
+       .read = i915_min_freq_read,
+       .write = i915_min_freq_write,
+       .llseek = default_llseek,
+};
+
+static ssize_t
 i915_cache_sharing_read(struct file *filp,
                   char __user *ubuf,
                   size_t max,
@@ -1997,6 +2055,12 @@ int i915_debugfs_init(struct drm_minor *minor)
                return ret;
 
        ret = i915_debugfs_create(minor->debugfs_root, minor,
+                                 "i915_min_freq",
+                                 &i915_min_freq_fops);
+       if (ret)
+               return ret;
+
+       ret = i915_debugfs_create(minor->debugfs_root, minor,
                                  "i915_cache_sharing",
                                  &i915_cache_sharing_fops);
        if (ret)
@@ -2028,6 +2092,8 @@ 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_min_freq_fops,
+                                1, minor);
        drm_debugfs_remove_files((struct drm_info_list *) &i915_cache_sharing_fops,
                                 1, minor);
        drm_debugfs_remove_files((struct drm_info_list *) &i915_ring_stop_fops,