Take into account whether or not the AGP aperture is
enabled or not when calculating the system aperture.

Fixes white screens with DCN 3.1.4.

Based on a patch from Yifan Zhang <[email protected]>

Cc: Yifan Zhang <[email protected]>
Acked-by: Harry Wentland <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 42 ++++++++++++-------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 1736a5488762..1f5b9c485dda 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1185,24 +1185,38 @@ static void mmhub_read_system_context(struct 
amdgpu_device *adev, struct dc_phy_
 
        memset(pa_config, 0, sizeof(*pa_config));
 
-       logical_addr_low  = min(adev->gmc.fb_start, adev->gmc.agp_start) >> 18;
-       pt_base = amdgpu_gmc_pd_addr(adev->gart.bo);
-
-       if (adev->apu_flags & AMD_APU_IS_RAVEN2)
-               /*
-                * Raven2 has a HW issue that it is unable to use the vram which
-                * is out of MC_VM_SYSTEM_APERTURE_HIGH_ADDR. So here is the
-                * workaround that increase system aperture high address (add 1)
-                * to get rid of the VM fault and hardware hang.
-                */
-               logical_addr_high = max((adev->gmc.fb_end >> 18) + 0x1, 
adev->gmc.agp_end >> 18);
-       else
-               logical_addr_high = max(adev->gmc.fb_end, adev->gmc.agp_end) >> 
18;
-
        agp_base = 0;
        agp_bot = adev->gmc.agp_start >> 24;
        agp_top = adev->gmc.agp_end >> 24;
 
+       /* AGP aperture is disabled */
+       if (agp_bot == agp_top) {
+               logical_addr_low  = adev->gmc.vram_start >> 18;
+               if (adev->apu_flags & AMD_APU_IS_RAVEN2)
+                       /*
+                        * Raven2 has a HW issue that it is unable to use the 
vram which
+                        * is out of MC_VM_SYSTEM_APERTURE_HIGH_ADDR. So here 
is the
+                        * workaround that increase system aperture high 
address (add 1)
+                        * to get rid of the VM fault and hardware hang.
+                        */
+                       logical_addr_high = (adev->gmc.fb_end >> 18) + 0x1;
+               else
+                       logical_addr_high = adev->gmc.vram_end >> 18;
+       } else {
+               logical_addr_low  = min(adev->gmc.fb_start, 
adev->gmc.agp_start) >> 18;
+               if (adev->apu_flags & AMD_APU_IS_RAVEN2)
+                       /*
+                        * Raven2 has a HW issue that it is unable to use the 
vram which
+                        * is out of MC_VM_SYSTEM_APERTURE_HIGH_ADDR. So here 
is the
+                        * workaround that increase system aperture high 
address (add 1)
+                        * to get rid of the VM fault and hardware hang.
+                        */
+                       logical_addr_high = max((adev->gmc.fb_end >> 18) + 0x1, 
adev->gmc.agp_end >> 18);
+               else
+                       logical_addr_high = max(adev->gmc.fb_end, 
adev->gmc.agp_end) >> 18;
+       }
+
+       pt_base = amdgpu_gmc_pd_addr(adev->gart.bo);
 
        page_table_start.high_part = (u32)(adev->gmc.gart_start >> 44) & 0xF;
        page_table_start.low_part = (u32)(adev->gmc.gart_start >> 12);
-- 
2.39.1

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