The GEN FBC unit provides the ability to set a low pass on frames it
attempts to compress. If a frame is less than a certain amount
compressibility (2:1, 4:1) it will not bother. This allows the driver to
reduce the size it requests out of stolen memory.
Unluckily, a few months ago, Ville actually began using this feature for
framebuffers that are 16bpp (not sure why not 8bpp). In those cases, we
are already using this mechanism for a different purpose, and so we can
only achieve one further level of compression (2:1 -> 4:1)
FBC GEN1, ie. pre-G45 is ignored.
The cleverness of the patch is Art's. The bugs are mine.
Cc: Art Runyan <arthur.j.runyan@xxxxxxxxx>
Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 3 +-
drivers/gpu/drm/i915/i915_gem_stolen.c | 54 +++++++++++++++++++++++++---------
drivers/gpu/drm/i915/intel_pm.c | 28 ++++++++++++++++--
3 files changed, 67 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0003206..db9dac4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -601,6 +601,7 @@ struct intel_context {
struct i915_fbc {
unsigned long size;
+ unsigned threshold;
unsigned int fb_id;
enum plane plane;
int y;
@@ -2446,7 +2447,7 @@ static inline void i915_gem_chipset_flush(struct drm_device *dev)
/* i915_gem_stolen.c */
int i915_gem_init_stolen(struct drm_device *dev);
-int i915_gem_stolen_setup_compression(struct drm_device *dev, int size);
+int i915_gem_stolen_setup_compression(struct drm_device *dev, int size, int fb_cpp);
void i915_gem_stolen_cleanup_compression(struct drm_device *dev);
void i915_gem_cleanup_stolen(struct drm_device *dev);
struct drm_i915_gem_object *
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index a86b331..4b9804e 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -105,35 +105,61 @@ static unsigned long i915_stolen_to_physical(struct drm_device *dev)
static int find_compression_threshold(struct drm_device *dev,
struct drm_mm_node *node,
- int size)
+ int size,
+ int fb_cpp)
{
struct drm_i915_private *dev_priv = dev->dev_private;
- const int compression_threshold = 1;
+ int compression_threshold = 1;
int ret;
- /* Try to over-allocate to reduce reallocations and fragmentation */
+ /* HACK: This code depends on what we will do in *_enable_fbc. If that
+ * code changes, this code needs to change as well.
+ *
+ * The enable_fbc code will attempt to use one of our 2 compression
+ * thresholds, therefore, in that case, we only have 1 resort.
+ */
+
+ /* Try to over-allocate to reduce reallocations and fragmentation. */
ret = drm_mm_insert_node(&dev_priv->mm.stolen, node,
size <<= 1, 4096, DRM_MM_SEARCH_DEFAULT);
- if (ret)
- ret = drm_mm_insert_node(&dev_priv->mm.stolen, node,
- size >>= 1, 4096,
- DRM_MM_SEARCH_DEFAULT);
- if (ret)
+ if (ret == 0)
+ return compression_threshold;
+
+again:
+ /* HW's ability to limit the CFB is 1:4 */
+ if (compression_threshold > 4 ||
+ (fb_cpp == 2 && compression_threshold == 2))
return 0;
- else
+
+ ret = drm_mm_insert_node(&dev_priv->mm.stolen, node,
+ size >>= 1, 4096,
+ DRM_MM_SEARCH_DEFAULT);
+ if (ret && INTEL_INFO(dev)->gen <= 4) {
+ return 0;
+ } else if (ret) {
+ compression_threshold <<= 1;
+ goto again;
+ } else {
return compression_threshold;
+ }
}
-static int i915_setup_compression(struct drm_device *dev, int size)
+static int i915_setup_compression(struct drm_device *dev, int size, int fb_cpp)
{
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_mm_node *uninitialized_var(compressed_llb);
int ret;
ret = find_compression_threshold(dev, &dev_priv->fbc.compressed_fb,
- size);
+ size, fb_cpp);
if (!ret)
goto err_llb;
+ else if (ret > 1) {
+ DRM_INFO("Reducing the compressed framebuffer size. This may lead to increased power. Try to increase stolen memory size if available in BIOS.\n");
+
+ }
+
+ dev_priv->fbc.threshold = ret;
if (HAS_PCH_SPLIT(dev))
I915_WRITE(ILK_DPFC_CB_BASE, dev_priv->fbc.compressed_fb.start);
@@ -157,7 +183,7 @@ static int i915_setup_compression(struct drm_device *dev, int size)
dev_priv->mm.stolen_base + compressed_llb->start);
}
- dev_priv->fbc.size = size;
+ dev_priv->fbc.size = size / dev_priv->fbc.threshold;
DRM_DEBUG_KMS("reserved %d bytes of contiguous stolen space for FBC\n",
size);
@@ -172,7 +198,7 @@ err_llb:
return -ENOSPC;
}
-int i915_gem_stolen_setup_compression(struct drm_device *dev, int size)
+int i915_gem_stolen_setup_compression(struct drm_device *dev, int size, int fb_cpp)
{
struct drm_i915_private *dev_priv = dev->dev_private;
@@ -185,7 +211,7 @@ int i915_gem_stolen_setup_compression(struct drm_device *dev, int size)
/* Release any current block */
i915_gem_stolen_cleanup_compression(dev);
- return i915_setup_compression(dev, size);
+ return i915_setup_compression(dev, size, fb_cpp);
}
void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2043c4b..340ca3a 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -229,9 +229,19 @@ static void ironlake_enable_fbc(struct drm_crtc *crtc)
dpfc_ctl = DPFC_CTL_PLANE(intel_crtc->plane);
if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
+ dev_priv->fbc.threshold++;
+
+ switch (dev_priv->fbc.threshold) {
+ case 4:
+ dpfc_ctl |= DPFC_CTL_LIMIT_4X;
+ break;
+ case 2:
dpfc_ctl |= DPFC_CTL_LIMIT_2X;
- else
+ break;
+ case 1:
dpfc_ctl |= DPFC_CTL_LIMIT_1X;
+ break;
+ }
dpfc_ctl |= DPFC_CTL_FENCE_EN;
if (IS_GEN5(dev))
dpfc_ctl |= obj->fence_reg;
@@ -285,9 +295,20 @@ static void gen7_enable_fbc(struct drm_crtc *crtc)
dpfc_ctl = IVB_DPFC_CTL_PLANE(intel_crtc->plane);
if (drm_format_plane_cpp(fb->pixel_format, 0) == 2)
+ dev_priv->fbc.threshold++;
+
+ switch (dev_priv->fbc.threshold) {
+ case 4:
+ dpfc_ctl |= DPFC_CTL_LIMIT_4X;
+ break;
+ case 2:
dpfc_ctl |= DPFC_CTL_LIMIT_2X;
- else
+ break;
+ case 1:
dpfc_ctl |= DPFC_CTL_LIMIT_1X;
+ break;
+ }
+
dpfc_ctl |= IVB_DPFC_CTL_FENCE_EN;
I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);
@@ -566,7 +587,8 @@ void intel_update_fbc(struct drm_device *dev)
if (in_dbg_master())
goto out_disable;
- if (i915_gem_stolen_setup_compression(dev, intel_fb->obj->base.size)) {
+ if (i915_gem_stolen_setup_compression(dev, intel_fb->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;
--
2.0.0
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