drm/amdgpu: add VRAM manager v2

Split VRAM allocations into 4MB blocks.

v2: fix typo in comment, some suggested cleanups
v3: document how to disable the feature, fix rebase issue

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 039b57e..1296f59 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -97,6 +97,7 @@ extern char *amdgpu_disable_cu;
 extern int amdgpu_sclk_deep_sleep_en;
 extern char *amdgpu_virtual_display;
 extern unsigned amdgpu_pp_feature_mask;
+extern int amdgpu_vram_page_split;
 
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS	        3000
 #define AMDGPU_MAX_USEC_TIMEOUT			100000	/* 100 ms */