[Intel-gfx] [PATCH 1/3] drm/i915/skl+: Don't trust cached ddb values

[Mahesh Kumar]

Don't trust cached DDB values. Recalculate the ddb value if cached value
is zero.

If i915 is build as a module, there may be a race condition when
cursor_disable call comes even before intel_fbdev_initial_config.
Which may lead to cached value being 0. And further commit will fail
until a modeset.

Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 936eef1634c7..b67be1355e39 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3721,6 +3721,7 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct drm_crtc *for_crtc = cstate->base.crtc;
 	unsigned int pipe_size, ddb_size;
+	unsigned int active_crtcs;
 	int nth_active_pipe;
 
 	if (WARN_ON(!state) || !cstate->base.active) {
@@ -3731,10 +3732,11 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 	}
 
 	if (intel_state->active_pipe_changes)
-		*num_active = hweight32(intel_state->active_crtcs);
+		active_crtcs = intel_state->active_crtcs;
 	else
-		*num_active = hweight32(dev_priv->active_crtcs);
+		active_crtcs = dev_priv->active_crtcs;
 
+	*num_active = hweight32(active_crtcs);
 	ddb_size = INTEL_INFO(dev_priv)->ddb_size;
 	WARN_ON(ddb_size == 0);
 
@@ -3754,12 +3756,15 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 		 * copy from old state to be sure
 		 */
 		*alloc = to_intel_crtc_state(for_crtc->state)->wm.skl.ddb;
-		return;
+		if (!skl_ddb_entry_size(alloc))
+			DRM_DEBUG_KMS("Cached pipe DDB is 0 recalculate\n");
+		else
+			return;
 	}
 
-	nth_active_pipe = hweight32(intel_state->active_crtcs &
+	nth_active_pipe = hweight32(active_crtcs &
 				    (drm_crtc_mask(for_crtc) - 1));
-	pipe_size = ddb_size / hweight32(intel_state->active_crtcs);
+	pipe_size = ddb_size / hweight32(active_crtcs);
 	alloc->start = nth_active_pipe * ddb_size / *num_active;
 	alloc->end = alloc->start + pipe_size;
 }
-- 
2.11.0