drm/i915: disable FBC when more than one pipe is active

We're really supposed to do this to avoid trouble with underflows when
multiple planes are active.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=26987.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: fangxun <xunx.fang@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

3 files changed, 19 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index aee83fa178f6..9214119c0154 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -605,6 +605,9 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
                 case FBC_NOT_TILED:
                         seq_printf(m, "scanout buffer not tiled");
                         break;
+                case FBC_MULTIPLE_PIPES:
+                        seq_printf(m, "multiple pipes are enabled");
+                        break;
                 default:
                         seq_printf(m, "unknown reason");
                 }
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d147ab2f5bfc..1d82de1618ab 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -215,6 +215,7 @@ enum no_fbc_reason {
         FBC_MODE_TOO_LARGE, /* mode too large for compression */
         FBC_BAD_PLANE, /* fbc not supported on plane */
         FBC_NOT_TILED, /* buffer not tiled */
+        FBC_MULTIPLE_PIPES, /* more than one pipe active */
 };
 
 enum intel_pch {
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a37d4cea98a6..30d8dafb388d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1180,8 +1180,12 @@ static void intel_update_fbc(struct drm_crtc *crtc,
         struct drm_framebuffer *fb = crtc->fb;
         struct intel_framebuffer *intel_fb;
         struct drm_i915_gem_object *obj_priv;
+        struct drm_crtc *tmp_crtc;
         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
         int plane = intel_crtc->plane;
+        int crtcs_enabled = 0;
+
+        DRM_DEBUG_KMS("\n");
 
         if (!i915_powersave)
                 return;
@@ -1199,10 +1203,21 @@ static void intel_update_fbc(struct drm_crtc *crtc,
          * If FBC is already on, we just have to verify that we can
          * keep it that way...
          * Need to disable if:
+         *   - more than one pipe is active
          *   - changing FBC params (stride, fence, mode)
          *   - new fb is too large to fit in compressed buffer
          *   - going to an unsupported config (interlace, pixel multiply, etc.)
          */
+        list_for_each_entry(tmp_crtc, &dev->mode_config.crtc_list, head) {
+                if (tmp_crtc->enabled)
+                        crtcs_enabled++;
+        }
+        DRM_DEBUG_KMS("%d pipes active\n", crtcs_enabled);
+        if (crtcs_enabled > 1) {
+                DRM_DEBUG_KMS("more than one pipe active, disabling compression\n");
+                dev_priv->no_fbc_reason = FBC_MULTIPLE_PIPES;
+                goto out_disable;
+        }
         if (intel_fb->obj->size > dev_priv->cfb_size) {
                 DRM_DEBUG_KMS("framebuffer too large, disabling "
                                 "compression\n");