[PATCH 4/9] drm/i915: don't free the CFB while FBC is enabled

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

Because that is probably not very a good idea: if we used the stolen
memory for more things, there could be a risk that someone would
"allocate" the memory that the HW is still using as the CFB while FBC
was still enabled.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_stolen.c |  3 +++
 drivers/gpu/drm/i915/intel_fbc.c       | 14 +++++++-------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index d02c102..f84c5f3 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -198,6 +198,8 @@ static int i915_setup_compression(struct drm_device *dev, int size, int fb_cpp)
 	struct drm_mm_node *uninitialized_var(compressed_llb);
 	int ret;
 
+	WARN_ON(dev_priv->fbc.enabled);
+
 	ret = find_compression_threshold(dev, &dev_priv->fbc.compressed_fb,
 					 size, fb_cpp);
 	if (!ret)
@@ -268,6 +270,7 @@ void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
 	if (dev_priv->fbc.compressed_fb.allocated == 0)
 		return;
 
+	WARN_ON(dev_priv->fbc.enabled);
 	drm_mm_remove_node(&dev_priv->fbc.compressed_fb);
 
 	if (dev_priv->fbc.compressed_llb) {
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 1b10b06..83d3c8a 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -593,13 +593,6 @@ void intel_fbc_update(struct drm_device *dev)
 	if (in_dbg_master())
 		goto out_disable;
 
-	if (i915_gem_stolen_setup_compression(dev, obj->base.size,
-					      drm_format_plane_cpp(fb->pixel_format, 0))) {
-		if (set_no_fbc_reason(dev_priv, FBC_STOLEN_TOO_SMALL))
-			DRM_DEBUG_KMS("framebuffer too large, disabling compression\n");
-		goto out_disable;
-	}
-
 	/* If the scanout has not changed, don't modify the FBC settings.
 	 * Note that we make the fundamental assumption that the fb->obj
 	 * cannot be unpinned (and have its GTT offset and fence revoked)
@@ -638,6 +631,13 @@ void intel_fbc_update(struct drm_device *dev)
 		intel_fbc_disable(dev);
 	}
 
+	if (i915_gem_stolen_setup_compression(dev, obj->base.size,
+					      drm_format_plane_cpp(fb->pixel_format, 0))) {
+		if (set_no_fbc_reason(dev_priv, FBC_STOLEN_TOO_SMALL))
+			DRM_DEBUG_KMS("framebuffer too large, disabling compression\n");
+		return;
+	}
+
 	intel_fbc_enable(crtc);
 	dev_priv->fbc.no_fbc_reason = FBC_OK;
 	return;
-- 
2.1.3

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