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.run...@intel.com
Signed-off-by: Ben Widawsky b...@bwidawsk.net
---
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
