On Mon, 2024-08-26 at 11:50 +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.
>
> 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 */
A first time reader would wonder "Affected by what". Could we rephrase
like "This specific format, only available with DGFX needs .." or
something similar self-contained?
> + 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))
This might probably fail on 32-bit compiles? Can we use the IS_ALIGNED
macro?
> + 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) ||
Otherwise LGTM.
/Thomas
