[PATCH] drm/amd/amdgpu: set gtt size according to system memory size only

[Roger He]

Change-Id: Ib634375b90d875fe04a890fc82fb1e3b7112676a
Signed-off-by: Roger He <Hongbo.He at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 17bf0ce..d773c5e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1328,13 +1328,19 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
 
 	if (amdgpu_gtt_size == -1) {
 		struct sysinfo si;
+		uint64_t sys_mem_size;
 
 		si_meminfo(&si);
-		gtt_size = min(max((AMDGPU_DEFAULT_GTT_SIZE_MB << 20),
-			       adev->mc.mc_vram_size),
-			       ((uint64_t)si.totalram * si.mem_unit * 3/4));
-	}
-	else
+		sys_mem_size = (uint64_t)si.totalram * si.mem_unit;
+		gtt_size = AMDGPU_DEFAULT_GTT_SIZE_MB << 20;
+
+		/* leave 2GB for OS to work with */
+		if (sys_mem_size > (2ULL << 30)) {
+			gtt_size = max(gtt_size, sys_mem_size - (2ULL << 30));
+		} else
+			DRM_INFO("amdgpu: Too small system memory %llu MB\n",
+				sys_mem_size >> 20);
+	} else
 		gtt_size = (uint64_t)amdgpu_gtt_size << 20;
 	r = ttm_bo_init_mm(&adev->mman.bdev, TTM_PL_TT, gtt_size >> PAGE_SHIFT);
 	if (r) {
-- 
2.7.4