Revert "drm/amd: Disable S/G for APUs when 64GB or more host memory"

This reverts commit 70e64c4d.

Since, we now have an actual fix for this issue, we can get rid of this
workaround as it can cause pin failures if enough VRAM isn't carved out
by the BIOS.

Cc: stable@vger.kernel.org # 6.1+
Acked-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1315,7 +1315,6 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
 void amdgpu_device_pci_config_reset(struct amdgpu_device *adev);
 int amdgpu_device_pci_reset(struct amdgpu_device *adev);
 bool amdgpu_device_need_post(struct amdgpu_device *adev);
-bool amdgpu_sg_display_supported(struct amdgpu_device *adev);
 bool amdgpu_device_pcie_dynamic_switching_supported(void);
 bool amdgpu_device_should_use_aspm(struct amdgpu_device *adev);
 bool amdgpu_device_aspm_support_quirk(void);

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

@@ -1358,32 +1358,6 @@ bool amdgpu_device_need_post(struct amdgpu_device *adev)
 	return true;
 }
 
-/*
- * On APUs with >= 64GB white flickering has been observed w/ SG enabled.
- * Disable S/G on such systems until we have a proper fix.
- * https://gitlab.freedesktop.org/drm/amd/-/issues/2354
- * https://gitlab.freedesktop.org/drm/amd/-/issues/2735
- */
-bool amdgpu_sg_display_supported(struct amdgpu_device *adev)
-{
-	switch (amdgpu_sg_display) {
-	case -1:
-		break;
-	case 0:
-		return false;
-	case 1:
-		return true;
-	default:
-		return false;
-	}
-	if ((totalram_pages() << (PAGE_SHIFT - 10)) +
-	    (adev->gmc.real_vram_size / 1024) >= 64000000) {
-		DRM_WARN("Disabling S/G due to >=64GB RAM\n");
-		return false;
-	}
-	return true;
-}
-
 /*
  * Intel hosts such as Raptor Lake and Sapphire Rapids don't support dynamic
  * speed switching. Until we have confirmation from Intel that a specific host

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1654,8 +1654,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 		}
 		break;
 	}
-	if (init_data.flags.gpu_vm_support)
-		init_data.flags.gpu_vm_support = amdgpu_sg_display_supported(adev);
+	if (init_data.flags.gpu_vm_support &&
+	    (amdgpu_sg_display == 0))
+		init_data.flags.gpu_vm_support = false;
 
 	if (init_data.flags.gpu_vm_support)
 		adev->mode_info.gpu_vm_support = true;