[PATCH v2] drm/amdgpu: Limit the max mc address to hole start

[Emily Deng]

Replace AMDGPU_VA_HOLE_START with AMDGPU_GMC_HOLE_START, and add the comment in
code.

For the vram_start is 0 case, the gart range will be from 0x0000FFFF00000000
to 0x0000FFFF1FFFFFFF, which will cause the engine hang.

So to avoid the hole, limit the max mc address to AMDGPU_GMC_HOLE_START.

Signed-off-by: Emily Deng <Emily.Deng at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index 9a5b252..bb05d9b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -146,6 +146,8 @@ void amdgpu_gmc_gart_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc)
 {
 	const uint64_t four_gb = 0x100000000ULL;
 	u64 size_af, size_bf;
+	/*To avoid the hole, limit the max mc address to AMDGPU_GMC_HOLE_START*/
+	u64 max_mc_address = min(adev->gmc.mc_mask, AMDGPU_GMC_HOLE_START);
 
 	mc->gart_size += adev->pm.smu_prv_buffer_size;
 
@@ -153,7 +155,7 @@ 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->fb_start;
-	size_af = adev->gmc.mc_mask + 1 - ALIGN(mc->fb_end + 1, four_gb);
+	size_af = max_mc_address + 1 - ALIGN(mc->fb_end + 1, four_gb);
 
 	if (mc->gart_size > max(size_bf, size_af)) {
 		dev_warn(adev->dev, "limiting GART\n");
@@ -164,7 +166,7 @@ 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 = mc->mc_mask - mc->gart_size + 1;
+		mc->gart_start = max_mc_address - mc->gart_size + 1;
 
 	mc->gart_start &= ~(four_gb - 1);
 	mc->gart_end = mc->gart_start + mc->gart_size - 1;
-- 
2.7.4