On Mon, Aug 26, 2024 at 11:50:40AM +0200, Maarten Lankhorst wrote:
> For CCS formats on affected platforms, CCS can be used freely, but
> display engine requires a multiple of 64k physical pages. No other
> changes are needed.
>
> At the BO creation time we don't know if the BO will be used for CCS
> or not. If the scanout flag is set, and the BO is a multiple of 64k,
> we take the safe route and force the physical alignment of 64k pages.
>
> If the BO is not a multiple of 64k, or the scanout flag was not set
> at BO creation, we reject it for usage as CCS in display. The physical
> pages are likely not aligned correctly, and this will cause corruption
> when used as FB.
>
> The scanout flag and size being a multiple of 64k are used together
> to enforce 64k physical placement.
>
> VM_BIND is completely unaffected, mappings to a VM can still be aligned
> to 4k, just like for normal buffers.
For me patch and explanation looks correct. According to submitting
patches rules please add my s-o-b before the merge.
--
Zbigniew
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Co-developed-by: Zbigniew Kempczyński <zbigniew.kempczynski@xxxxxxxxx>
> Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila@xxxxxxxxx>
> ---
> drivers/gpu/drm/xe/display/intel_fb_bo.c | 5 +++++
> drivers/gpu/drm/xe/xe_bo.c | 7 +++++++
> drivers/gpu/drm/xe/xe_vm.c | 11 ++++++++++-
> 3 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/display/intel_fb_bo.c b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> index f835492f73fb4..6775c2557b9df 100644
> --- a/drivers/gpu/drm/xe/display/intel_fb_bo.c
> +++ b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> @@ -28,6 +28,11 @@ int intel_fb_bo_framebuffer_init(struct intel_framebuffer *intel_fb,
> struct xe_device *xe = to_xe_device(bo->ttm.base.dev);
> int ret;
>
> + /* Only this specific format is affected, and it's only available on VRAM */
> + if (XE_IOCTL_DBG(xe, mode_cmd->modifier[0] == I915_FORMAT_MOD_4_TILED_BMG_CCS &&
> + !(bo->flags & XE_BO_FLAG_NEEDS_64K)))
> + return -EINVAL;
> +
> xe_bo_get(bo);
>
> ret = ttm_bo_reserve(&bo->ttm, true, false, NULL);
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index cbe7bf098970f..41297b5797173 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -2019,6 +2019,13 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
>
> bo_flags |= args->placement << (ffs(XE_BO_FLAG_SYSTEM) - 1);
>
> + /* CCS formats need physical placement at a 64K alignment in VRAM. */
> + if ((bo_flags & XE_BO_FLAG_VRAM_MASK) &&
> + (bo_flags & XE_BO_FLAG_SCANOUT) &&
> + !(xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K) &&
> + !(args->size % SZ_64K))
> + bo_flags |= XE_BO_FLAG_NEEDS_64K;
> +
> if (args->flags & DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM) {
> if (XE_IOCTL_DBG(xe, !(bo_flags & XE_BO_FLAG_VRAM_MASK)))
> return -EINVAL;
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 4cc13eddb6b32..3eb76d874eb28 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -2878,7 +2878,16 @@ static int xe_vm_bind_ioctl_validate_bo(struct xe_device *xe, struct xe_bo *bo,
> return -EINVAL;
> }
>
> - if (bo->flags & XE_BO_FLAG_INTERNAL_64K) {
> + /*
> + * Some platforms require 64k VM_BIND alignment,
> + * specifically those with XE_VRAM_FLAGS_NEED64K.
> + *
> + * Other platforms may have BO's set to 64k physical placement,
> + * but can be mapped at 4k offsets anyway. This check is only
> + * there for the former case.
> + */
> + if ((bo->flags & XE_BO_FLAG_INTERNAL_64K) &&
> + (xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K)) {
> if (XE_IOCTL_DBG(xe, obj_offset &
> XE_64K_PAGE_MASK) ||
> XE_IOCTL_DBG(xe, addr & XE_64K_PAGE_MASK) ||
> --
> 2.45.2
>
