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

[Ben Hutchings]

From: Jesse Barnes <jbarnes at virtuousgeek.org>

commit 9c928d168d4030a230a7a5ee1764721d173f1153 upstream.

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 at virtuousgeek.org>
Tested-by: fangxun <xunx.fang at intel.com>
Signed-off-by: Eric Anholt <eric at anholt.net>
[bwh: Backport to DRM 2.6.33 - drop debugfs integration.]
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
---
 drivers/gpu/drm/i915/intel_display.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 26e7d22..1a671b7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1160,8 +1160,12 @@ 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;
@@ -1181,10 +1185,20 @@ 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");
+		goto out_disable;
+	}
 	if (intel_fb->obj->size > dev_priv->cfb_size) {
 		DRM_DEBUG_KMS("framebuffer too large, disabling "
 				"compression\n");
-- 
1.7.1


-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.