drm/amdgpu: put GART away from VRAM v2

Always try to put the GART away from where VRAM is.

v2: correctly handle the 4GB limitation

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index 265ec6807130..c6bcc4715373 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -116,6 +116,7 @@ void amdgpu_gmc_vram_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc,
  */
 void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
 {
+        const uint64_t four_gb = 0x100000000ULL;
         u64 size_af, size_bf;
 
         mc->gart_size += adev->pm.smu_prv_buffer_size;
@@ -124,8 +125,7 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
          * the GART base on a 4GB boundary as well.
          */
         size_bf = mc->vram_start;
-        size_af = adev->gmc.mc_mask + 1 -
-                ALIGN(mc->vram_end + 1, 0x100000000ULL);
+        size_af = adev->gmc.mc_mask + 1 - ALIGN(mc->vram_end + 1, four_gb);
 
         if (mc->gart_size > max(size_bf, size_af)) {
                 dev_warn(adev->dev, "limiting GART\n");
@@ -136,7 +136,9 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
             (size_af < mc->gart_size))
                 mc->gart_start = 0;
         else
-                mc->gart_start = ALIGN(mc->vram_end + 1, 0x100000000ULL);
+                mc->gart_start = mc->mc_mask - mc->gart_size + 1;
+
+        mc->gart_start &= four_gb - 1;
         mc->gart_end = mc->gart_start + mc->gart_size - 1;
         dev_info(adev->dev, "GART: %lluM 0x%016llX - 0x%016llX\n",
                         mc->gart_size >> 20, mc->gart_start, mc->gart_end);