Commit 92b88aeb authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Not all mappable regions require GTT fence regions 



Combining map_and_fenceable revealed a bug in
i915_gem_object_gtt_size() in that it always computed the appropriate
fence size for the object regardless of tiling state which caused us to
over-allocate linear buffers when binding to the GTT.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
parent 05394f39

drivers/gpu/drm/i915/i915_gem.c

+22 −31
Original line number Diff line number Diff line
@@ -41,9 +41,6 @@ struct change_domains { 
	uint32_t flush_rings;

};



static uint32_t i915_gem_get_gtt_alignment(struct drm_i915_gem_object *obj);

static uint32_t i915_gem_get_gtt_size(struct drm_i915_gem_object *obj);



static int i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj,

						  bool pipelined);

static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
@@ -1443,6 +1440,28 @@ i915_gem_free_mmap_offset(struct drm_i915_gem_object *obj) 
	list->map = NULL;

}



static uint32_t

i915_gem_get_gtt_size(struct drm_i915_gem_object *obj)

{

	struct drm_device *dev = obj->base.dev;

	uint32_t size;



	if (INTEL_INFO(dev)->gen >= 4 ||

	    obj->tiling_mode == I915_TILING_NONE)

		return obj->base.size;



	/* Previous chips need a power-of-two fence region when tiling */

	if (INTEL_INFO(dev)->gen == 3)

		size = 1024*1024;

	else

		size = 512*1024;



	while (size < obj->base.size)

		size <<= 1;



	return size;

}



/**

 * i915_gem_get_gtt_alignment - return required GTT alignment for an object

 * @obj: object to check
@@ -1505,34 +1524,6 @@ i915_gem_get_unfenced_gtt_alignment(struct drm_i915_gem_object *obj) 
	return tile_height * obj->stride * 2;

}



static uint32_t

i915_gem_get_gtt_size(struct drm_i915_gem_object *obj)

{

	struct drm_device *dev = obj->base.dev;

	uint32_t size;



	/*

	 * Minimum alignment is 4k (GTT page size), but might be greater

	 * if a fence register is needed for the object.

	 */

	if (INTEL_INFO(dev)->gen >= 4)

		return obj->base.size;



	/*

	 * Previous chips need to be aligned to the size of the smallest

	 * fence register that can contain the object.

	 */

	if (INTEL_INFO(dev)->gen == 3)

		size = 1024*1024;

	else

		size = 512*1024;



	while (size < obj->base.size)

		size <<= 1;



	return size;

}



/**

 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing

 * @dev: DRM device

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