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

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>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index a3b86b86dc477ca09cd3391cb332786c764d8008..6dc950c1b68933cbedfadf8034e736168e3595c3 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1296,6 +1296,7 @@ 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 a2cdde0ca0a72f42ef7cc4e2929fda910c066548..45e9d737e5b81baf226fbe581d7845b0123a7b4d 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -1458,6 +1458,32 @@ 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 0fa739fd6a9ca5329f117cf9a4e6219fe50b4a3a..e5554a36e8c8b2c7d8e43bc9b19c722941dfad83 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1638,9 +1638,8 @@ 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;