On Tue, 2022-04-12 at 15:18 +0000, Robert Beckett wrote:
> ttm managed buffers start off with system resource definitions and
> ttm_tt
> tracking structures allocated (though unpopulated).
> currently this prevents clearing of buffers on first move to desired
> placements.
>
> The desired behaviour is to clear user allocated buffers and any
> kernel
> buffers that specifically requests it only.
> Make the logic match the desired behaviour.
>
> Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx>
Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c | 22
> +++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> index 9fe8132de3b2..9cf85f91edb5 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
> @@ -3,6 +3,7 @@
> * Copyright © 2021 Intel Corporation
> */
>
> +#include "drm/ttm/ttm_tt.h"
> #include <drm/ttm/ttm_bo_driver.h>
>
> #include "i915_deps.h"
> @@ -470,6 +471,25 @@ __i915_ttm_move(struct ttm_buffer_object *bo,
> return fence;
> }
>
> +static bool
> +allow_clear(struct drm_i915_gem_object *obj, struct ttm_tt *ttm,
> struct ttm_resource *dst_mem)
> +{
> + /* never clear stolen */
> + if (dst_mem->mem_type == I915_PL_STOLEN)
> + return false;
> + /*
> + * we want to clear user buffers and any kernel buffers
> + * that specifically request clearing.
> + */
> + if (obj->flags & I915_BO_ALLOC_USER)
> + return true;
> +
> + if (ttm && ttm->page_flags & TTM_TT_FLAG_ZERO_ALLOC)
> + return true;
> +
> + return false;
> +}
> +
> /**
> * i915_ttm_move - The TTM move callback used by i915.
> * @bo: The buffer object.
> @@ -520,7 +540,7 @@ int i915_ttm_move(struct ttm_buffer_object *bo,
> bool evict,
> return PTR_ERR(dst_rsgt);
>
> clear = !i915_ttm_cpu_maps_iomem(bo->resource) && (!ttm ||
> !ttm_tt_is_populated(ttm));
> - if (!(clear && ttm && !(ttm->page_flags &
> TTM_TT_FLAG_ZERO_ALLOC))) {
> + if (!clear || allow_clear(obj, ttm, dst_mem)) {
> struct i915_deps deps;
>
> i915_deps_init(&deps, GFP_KERNEL | __GFP_NORETRY |
> __GFP_NOWARN);
