drm/i915: allow cache sharing policy control
Expose the SNB+ cache sharing policy register in debugfs. The new file,
i915_cache_sharing, has 4 values, 0-3, with 0 being "max uncore
resources" and 3 being the minimum. Exposing this control should make
benchmarking easier and help us choose a good default.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5bf7bf5..a8ab626 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1408,6 +1408,85 @@
.llseek = default_llseek,
};
+static int
+i915_cache_sharing_open(struct inode *inode,
+ struct file *filp)
+{
+ filp->private_data = inode->i_private;
+ return 0;
+}
+
+static ssize_t
+i915_cache_sharing_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];
+ u32 snpcr;
+ int len;
+
+ mutex_lock(&dev_priv->dev->struct_mutex);
+ snpcr = I915_READ(GEN6_MBCUNIT_SNPCR);
+ mutex_unlock(&dev_priv->dev->struct_mutex);
+
+ len = snprintf(buf, sizeof (buf),
+ "%d\n", (snpcr & GEN6_MBC_SNPCR_MASK) >>
+ GEN6_MBC_SNPCR_SHIFT);
+
+ if (len > sizeof (buf))
+ len = sizeof (buf);
+
+ return simple_read_from_buffer(ubuf, max, ppos, buf, len);
+}
+
+static ssize_t
+i915_cache_sharing_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];
+ u32 snpcr;
+ 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);
+ }
+
+ if (val < 0 || val > 3)
+ return -EINVAL;
+
+ DRM_DEBUG_DRIVER("Manually setting uncore sharing to %d\n", val);
+
+ /* Update the cache sharing policy here as well */
+ snpcr = I915_READ(GEN6_MBCUNIT_SNPCR);
+ snpcr &= ~GEN6_MBC_SNPCR_MASK;
+ snpcr |= (val << GEN6_MBC_SNPCR_SHIFT);
+ I915_WRITE(GEN6_MBCUNIT_SNPCR, snpcr);
+
+ return cnt;
+}
+
+static const struct file_operations i915_cache_sharing_fops = {
+ .owner = THIS_MODULE,
+ .open = i915_cache_sharing_open,
+ .read = i915_cache_sharing_read,
+ .write = i915_cache_sharing_write,
+ .llseek = default_llseek,
+};
+
/* As the drm_debugfs_init() routines are called before dev->dev_private is
* allocated we need to hook into the minor for release. */
static int
@@ -1522,6 +1601,21 @@
return drm_add_fake_info_node(minor, ent, &i915_max_freq_fops);
}
+static int i915_cache_sharing_create(struct dentry *root, struct drm_minor *minor)
+{
+ struct drm_device *dev = minor->dev;
+ struct dentry *ent;
+
+ ent = debugfs_create_file("i915_cache_sharing",
+ S_IRUGO | S_IWUSR,
+ root, dev,
+ &i915_cache_sharing_fops);
+ if (IS_ERR(ent))
+ return PTR_ERR(ent);
+
+ return drm_add_fake_info_node(minor, ent, &i915_cache_sharing_fops);
+}
+
static struct drm_info_list i915_debugfs_list[] = {
{"i915_capabilities", i915_capabilities, 0},
{"i915_gem_objects", i915_gem_object_info, 0},
@@ -1578,6 +1672,9 @@
ret = i915_max_freq_create(minor->debugfs_root, minor);
if (ret)
return ret;
+ ret = i915_cache_sharing_create(minor->debugfs_root, minor);
+ if (ret)
+ return ret;
return drm_debugfs_create_files(i915_debugfs_list,
I915_DEBUGFS_ENTRIES,
@@ -1594,6 +1691,8 @@
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_cache_sharing_fops,
+ 1, minor);
}
#endif /* CONFIG_DEBUG_FS */