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, 5 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e879885f4754..a483f41e9f22 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1188,25 +1188,30 @@ static void intel_update_fbc(struct drm_crtc *crtc,
         if (intel_fb->obj->size > dev_priv->cfb_size) {
                 DRM_DEBUG_KMS("framebuffer too large, disabling "
                                 "compression\n");
+                dev_priv->no_fbc_reason = FBC_STOLEN_TOO_SMALL;
                 goto out_disable;
         }
         if ((mode->flags & DRM_MODE_FLAG_INTERLACE) ||
             (mode->flags & DRM_MODE_FLAG_DBLSCAN)) {
                 DRM_DEBUG_KMS("mode incompatible with compression, "
                                 "disabling\n");
+                dev_priv->no_fbc_reason = FBC_UNSUPPORTED_MODE;
                 goto out_disable;
         }
         if ((mode->hdisplay > 2048) ||
             (mode->vdisplay > 1536)) {
                 DRM_DEBUG_KMS("mode too large for compression, disabling\n");
+                dev_priv->no_fbc_reason = FBC_MODE_TOO_LARGE;
                 goto out_disable;
         }
         if ((IS_I915GM(dev) || IS_I945GM(dev)) && plane != 0) {
                 DRM_DEBUG_KMS("plane not 0, disabling compression\n");
+                dev_priv->no_fbc_reason = FBC_BAD_PLANE;
                 goto out_disable;
         }
         if (obj_priv->tiling_mode != I915_TILING_X) {
                 DRM_DEBUG_KMS("framebuffer not tiled, disabling compression\n");
+                dev_priv->no_fbc_reason = FBC_NOT_TILED;
                 goto out_disable;
         }