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Commit 5e59f717 authored by Ben Widawsky's avatar Ben Widawsky Committed by Jani Nikula
Browse files

drm/i915: Try harder to get FBC 



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.

v2: Update message and including missing threshold case 3 (Spotted by Arthur).

Cc: Art Runyan <arthur.j.runyan@intel.com>
Signed-off-by: default avatarBen Widawsky <ben@bwidawsk.net>
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
parent edc0fdbb

drivers/gpu/drm/i915/i915_drv.h

+2 −1
Original line number Diff line number Diff line
@@ -600,6 +600,7 @@ struct intel_context { 


struct i915_fbc {

	unsigned long size;

	unsigned threshold;

	unsigned int fb_id;

	enum plane plane;

	int y;
@@ -2487,7 +2488,7 @@ 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 *

drivers/gpu/drm/i915/i915_gem_stolen.c

+40 −14
Original line number Diff line number Diff line
@@ -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)

	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;



	ret = drm_mm_insert_node(&dev_priv->mm.stolen, node,

				 size >>= 1, 4096,

				 DRM_MM_SEARCH_DEFAULT);

	if (ret)

	if (ret && INTEL_INFO(dev)->gen <= 4) {

		return 0;

	else

	} 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 less power savings than a non-reduced-size. 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)

drivers/gpu/drm/i915/intel_pm.c

+27 −3
Original line number Diff line number Diff line
@@ -229,9 +229,20 @@ 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:

	case 3:

		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 +296,21 @@ 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:

	case 3:

		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);
@@ -567,7 +590,8 @@ 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;