On Thu, Jul 27, 2023 at 2:37 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
>
> 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: 81d0bcf990093 ("drm/amdgpu: make display pinning more flexible (v2)")
> Cc: Hamza Mahfooz <Hamza.Mahfooz@xxxxxxx>
> Cc: Roman Li <roman.li@xxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # 6.1.y: bf0207e172703 ("drm/amdgpu: add S/G display parameter")
> Cc: <stable@xxxxxxxxxxxxxxx> # 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@xxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
> ---
> v2->v3:
> * Account for the VRAM carveout
> v1->v2:
> * Fix updating mode_info as well
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 26 +++++++++++++++++++
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 ++--
> 3 files changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 93d0f4c7b560e..2e3c7c15cb8e3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1313,6 +1313,7 @@ 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 dc0e5227119b1..0d602abd32bad 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1296,6 +1296,32 @@ 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 77d970a2ee693..26c3eb7a9f882 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1639,9 +1639,8 @@ 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;
> --
> 2.25.1
>
