drm/i915: provide FBC status in debugfs

Tools like powertop want to check the current FBC status and report it
to the user.  So add a debugfs file indicating whether FBC is enabled,
and if not, why.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 49 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 55340de618e..96e8b9b2cb3 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -477,6 +477,54 @@ static int i915_drpc_info(struct seq_file *m, void *unused)
         return 0;
 }
 
+static int i915_fbc_status(struct seq_file *m, void *unused)
+{
+        struct drm_info_node *node = (struct drm_info_node *) m->private;
+        struct drm_device *dev = node->minor->dev;
+        struct drm_crtc *crtc;
+        drm_i915_private_t *dev_priv = dev->dev_private;
+        bool fbc_enabled = false;
+
+        if (!dev_priv->display.fbc_enabled) {
+                seq_printf(m, "FBC unsupported on this chipset\n");
+                return 0;
+        }
+
+        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+                if (!crtc->enabled)
+                        continue;
+                if (dev_priv->display.fbc_enabled(crtc))
+                        fbc_enabled = true;
+        }
+
+        if (fbc_enabled) {
+                seq_printf(m, "FBC enabled\n");
+        } else {
+                seq_printf(m, "FBC disabled: ");
+                switch (dev_priv->no_fbc_reason) {
+                case FBC_STOLEN_TOO_SMALL:
+                        seq_printf(m, "not enough stolen memory");
+                        break;
+                case FBC_UNSUPPORTED_MODE:
+                        seq_printf(m, "mode not supported");
+                        break;
+                case FBC_MODE_TOO_LARGE:
+                        seq_printf(m, "mode too large");
+                        break;
+                case FBC_BAD_PLANE:
+                        seq_printf(m, "FBC unsupported on plane");
+                        break;
+                case FBC_NOT_TILED:
+                        seq_printf(m, "scanout buffer not tiled");
+                        break;
+                default:
+                        seq_printf(m, "unknown reason");
+                }
+                seq_printf(m, "\n");
+        }
+        return 0;
+}
+
 static int
 i915_wedged_open(struct inode *inode,
                  struct file *filp)
@@ -599,6 +647,7 @@ static struct drm_info_list i915_debugfs_list[] = {
         {"i915_delayfreq_table", i915_delayfreq_table, 0},
         {"i915_inttoext_table", i915_inttoext_table, 0},
         {"i915_drpc_info", i915_drpc_info, 0},
+        {"i915_fbc_status", i915_fbc_status, 0},
 };
 #define I915_DEBUGFS_ENTRIES ARRAY_SIZE(i915_debugfs_list)