drm/amdgpu/gmc6-8: properly disable the AGP aperture

The BOT register needs to be larger than the TOP register
for this to be properly disabled.  The lower 22 bits
of the BOT address are always 0 and the lower 22 bits of
the TOP register are always 1 so you need to make
the upper bits of BOT larger than the upper bits of BOT.
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c

@@ -253,7 +253,7 @@ static void gmc_v6_0_mc_program(struct amdgpu_device *adev)
 	WREG32(mmMC_VM_SYSTEM_APERTURE_DEFAULT_ADDR,
 	       adev->mem_scratch.gpu_addr >> 12);
 	WREG32(mmMC_VM_AGP_BASE, 0);
-	WREG32(mmMC_VM_AGP_TOP, 0x0FFFFFFF);
+	WREG32(mmMC_VM_AGP_TOP, 0);
 	WREG32(mmMC_VM_AGP_BOT, 0x0FFFFFFF);
 
 	if (gmc_v6_0_wait_for_idle((void *)adev))

drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c

@@ -288,7 +288,7 @@ static void gmc_v7_0_mc_program(struct amdgpu_device *adev)
 	WREG32(mmMC_VM_SYSTEM_APERTURE_DEFAULT_ADDR,
 	       adev->mem_scratch.gpu_addr >> 12);
 	WREG32(mmMC_VM_AGP_BASE, 0);
-	WREG32(mmMC_VM_AGP_TOP, 0x0FFFFFFF);
+	WREG32(mmMC_VM_AGP_TOP, 0);
 	WREG32(mmMC_VM_AGP_BOT, 0x0FFFFFFF);
 	if (gmc_v7_0_wait_for_idle((void *)adev))
 		dev_warn(adev->dev, "Wait for MC idle timedout !\n");

drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c

@@ -473,7 +473,7 @@ static void gmc_v8_0_mc_program(struct amdgpu_device *adev)
 	}
 
 	WREG32(mmMC_VM_AGP_BASE, 0);
-	WREG32(mmMC_VM_AGP_TOP, 0x0FFFFFFF);
+	WREG32(mmMC_VM_AGP_TOP, 0);
 	WREG32(mmMC_VM_AGP_BOT, 0x0FFFFFFF);
 	if (gmc_v8_0_wait_for_idle((void *)adev))
 		dev_warn(adev->dev, "Wait for MC idle timedout !\n");