[Intel-gfx] [RFC 4/8] drm/i915/vlv: return EINVAL when computed watermark exceeds system limitation

[Chi Ding]

From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>

When computing normal watermarks in vlv_compute_wm(), if the value
is bigger than system limitation, return EINVAL

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Signed-off-by: Chi Ding <chix.ding at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 3e239af..3fb896a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1152,9 +1152,14 @@ static int vlv_compute_wm(struct intel_crtc *crtc)
 			int wm = vlv_compute_wm_level(plane, crtc, state, level);
 			int max_wm = plane->base.type == DRM_PLANE_TYPE_CURSOR ? 63 : 511;
 
-			/* hack */
-			if (WARN_ON(level == 0 && wm > max_wm))
-				wm = max_wm;
+			if (level == 0 && wm > max_wm) {
+				DRM_DEBUG_KMS("Requested display configuration "
+				"exceeds system watermark limitations\n");
+				DRM_DEBUG_KMS("Plane %d.%d: blocks required = %u/%u\n",
+					crtc->pipe,
+					drm_plane_index(&plane->base), wm, max_wm);
+				return -EINVAL;
+			}
 
 			if (wm > wm_state->fifo_size[wm_plane_id(plane)])
 				break;
-- 
1.8.0.1