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

commit 08fffa74d9772d9538338be3f304006c94dde6f0 upstream.

Users report a white flickering screen on multiple systems that
is tied to having 64GB or more memory.  When S/G is enabled pages
will get pinned to both VRAM carve out and system RAM leading to
this.

Until it can be fixed properly, disable S/G when 64GB of memory or
more is detected.  This will force pages to be pinned into VRAM.
This should fix white screen flickers but if VRAM pressure is
encountered may lead to black screens.  It's a trade-off for now.

Fixes: 81d0bcf99009 ("drm/amdgpu: make display pinning more flexible (v2)")
Cc: Hamza Mahfooz <Hamza.Mahfooz@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: <stable@vger.kernel.org> # 6.1.y: bf0207e172703 ("drm/amdgpu: add S/G display parameter")
Cc: <stable@vger.kernel.org> # 6.4.y
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2735
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2354
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index e0f146ddc5562a8cb812b9974f09930d79a198a2..9ecf20169912664f1db09c46f48e62156801d78d 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1263,6 +1263,7 @@ 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);

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 30c97ee3756368a9f6847fb2d1d11c98c5add780..773383e660e8c90b63eb5073ee6f882f1089efea 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1333,6 +1333,32 @@ 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

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 41dec9eb08f0db63089eb743ac4cd2ac45d644db..9f718b98da1f7b87bcbbc22297e8d6cc6d947848 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1634,9 +1634,8 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
                }
                break;
        }
-       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)
+               init_data.flags.gpu_vm_support = amdgpu_sg_display_supported(adev);
 
        if (init_data.flags.gpu_vm_support)
                adev->mode_info.gpu_vm_support = true;