On Thu, Dec 10, 2020 at 08:02:38AM +0000, Chris Wilson wrote:
> Relative timelines are relative to either the global or per-process
> HWSP, and so we can replace the absolute addressing with store-index
> variants for position invariance.
>
Can you explain the benifit of relative addressing? Why can't we also
use absolute? If we can always use absolute, I don't see the point
complicating the breadcrumb code.
Matt
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gt/gen8_engine_cs.c | 98 +++++++++++++++++-------
> drivers/gpu/drm/i915/gt/intel_timeline.h | 12 +++
> 2 files changed, 82 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> index ed88dc4de72c..386da26816d0 100644
> --- a/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/gen8_engine_cs.c
> @@ -502,7 +502,19 @@ gen8_emit_fini_breadcrumb_tail(struct i915_request *rq, u32 *cs)
>
> static u32 *emit_xcs_breadcrumb(struct i915_request *rq, u32 *cs)
> {
> - return gen8_emit_ggtt_write(cs, rq->fence.seqno, hwsp_offset(rq), 0);
> + struct intel_timeline *tl = rcu_dereference_protected(rq->timeline, 1);
> + unsigned int flags = MI_FLUSH_DW_OP_STOREDW;
> + u32 offset = hwsp_offset(rq);
> +
> + if (intel_timeline_is_relative(tl)) {
> + offset = offset_in_page(offset);
> + flags |= MI_FLUSH_DW_STORE_INDEX;
> + }
> + GEM_BUG_ON(offset & 7);
> + if (intel_timeline_is_global(tl))
> + offset |= MI_FLUSH_DW_USE_GTT;
> +
> + return __gen8_emit_flush_dw(cs, rq->fence.seqno, offset, flags);
> }
>
> u32 *gen8_emit_fini_breadcrumb_xcs(struct i915_request *rq, u32 *cs)
> @@ -512,6 +524,18 @@ u32 *gen8_emit_fini_breadcrumb_xcs(struct i915_request *rq, u32 *cs)
>
> u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs)
> {
> + struct intel_timeline *tl = rcu_dereference_protected(rq->timeline, 1);
> + unsigned int flags = PIPE_CONTROL_FLUSH_ENABLE | PIPE_CONTROL_CS_STALL;
> + u32 offset = hwsp_offset(rq);
> +
> + if (intel_timeline_is_relative(tl)) {
> + offset = offset_in_page(offset);
> + flags |= PIPE_CONTROL_STORE_DATA_INDEX;
> + }
> + GEM_BUG_ON(offset & 7);
> + if (intel_timeline_is_global(tl))
> + flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;
> +
> cs = gen8_emit_pipe_control(cs,
> PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
> PIPE_CONTROL_DEPTH_CACHE_FLUSH |
> @@ -519,26 +543,33 @@ u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs)
> 0);
>
> /* XXX flush+write+CS_STALL all in one upsets gem_concurrent_blt:kbl */
> - cs = gen8_emit_ggtt_write_rcs(cs,
> - rq->fence.seqno,
> - hwsp_offset(rq),
> - PIPE_CONTROL_FLUSH_ENABLE |
> - PIPE_CONTROL_CS_STALL);
> + cs = __gen8_emit_write_rcs(cs, rq->fence.seqno, offset, 0, flags);
>
> return gen8_emit_fini_breadcrumb_tail(rq, cs);
> }
>
> u32 *gen11_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs)
> {
> - cs = gen8_emit_ggtt_write_rcs(cs,
> - rq->fence.seqno,
> - hwsp_offset(rq),
> - PIPE_CONTROL_CS_STALL |
> - PIPE_CONTROL_TILE_CACHE_FLUSH |
> - PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
> - PIPE_CONTROL_DEPTH_CACHE_FLUSH |
> - PIPE_CONTROL_DC_FLUSH_ENABLE |
> - PIPE_CONTROL_FLUSH_ENABLE);
> + struct intel_timeline *tl = rcu_dereference_protected(rq->timeline, 1);
> + u32 offset = hwsp_offset(rq);
> + unsigned int flags;
> +
> + flags = (PIPE_CONTROL_CS_STALL |
> + PIPE_CONTROL_TILE_CACHE_FLUSH |
> + PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
> + PIPE_CONTROL_DEPTH_CACHE_FLUSH |
> + PIPE_CONTROL_DC_FLUSH_ENABLE |
> + PIPE_CONTROL_FLUSH_ENABLE);
> +
> + if (intel_timeline_is_relative(tl)) {
> + offset = offset_in_page(offset);
> + flags |= PIPE_CONTROL_STORE_DATA_INDEX;
> + }
> + GEM_BUG_ON(offset & 7);
> + if (intel_timeline_is_global(tl))
> + flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;
> +
> + cs = __gen8_emit_write_rcs(cs, rq->fence.seqno, offset, 0, flags);
>
> return gen8_emit_fini_breadcrumb_tail(rq, cs);
> }
> @@ -601,19 +632,30 @@ u32 *gen12_emit_fini_breadcrumb_xcs(struct i915_request *rq, u32 *cs)
>
> u32 *gen12_emit_fini_breadcrumb_rcs(struct i915_request *rq, u32 *cs)
> {
> - cs = gen12_emit_ggtt_write_rcs(cs,
> - rq->fence.seqno,
> - hwsp_offset(rq),
> - PIPE_CONTROL0_HDC_PIPELINE_FLUSH,
> - PIPE_CONTROL_CS_STALL |
> - PIPE_CONTROL_TILE_CACHE_FLUSH |
> - PIPE_CONTROL_FLUSH_L3 |
> - PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
> - PIPE_CONTROL_DEPTH_CACHE_FLUSH |
> - /* Wa_1409600907:tgl */
> - PIPE_CONTROL_DEPTH_STALL |
> - PIPE_CONTROL_DC_FLUSH_ENABLE |
> - PIPE_CONTROL_FLUSH_ENABLE);
> + struct intel_timeline *tl = rcu_dereference_protected(rq->timeline, 1);
> + u32 offset = hwsp_offset(rq);
> + unsigned int flags;
> +
> + flags = (PIPE_CONTROL_CS_STALL |
> + PIPE_CONTROL_TILE_CACHE_FLUSH |
> + PIPE_CONTROL_FLUSH_L3 |
> + PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH |
> + PIPE_CONTROL_DEPTH_CACHE_FLUSH |
> + /* Wa_1409600907:tgl */
> + PIPE_CONTROL_DEPTH_STALL |
> + PIPE_CONTROL_DC_FLUSH_ENABLE |
> + PIPE_CONTROL_FLUSH_ENABLE);
> +
> + if (intel_timeline_is_relative(tl)) {
> + offset = offset_in_page(offset);
> + flags |= PIPE_CONTROL_STORE_DATA_INDEX;
> + }
> + GEM_BUG_ON(offset & 7);
> + if (intel_timeline_is_global(tl))
> + flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;
> +
> + cs = __gen8_emit_write_rcs(cs, rq->fence.seqno, offset,
> + PIPE_CONTROL0_HDC_PIPELINE_FLUSH, flags);
>
> return gen12_emit_fini_breadcrumb_tail(rq, cs);
> }
> diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.h b/drivers/gpu/drm/i915/gt/intel_timeline.h
> index 69250de3a814..a3bdbff62e96 100644
> --- a/drivers/gpu/drm/i915/gt/intel_timeline.h
> +++ b/drivers/gpu/drm/i915/gt/intel_timeline.h
> @@ -79,6 +79,18 @@ intel_timeline_has_initial_breadcrumb(const struct intel_timeline *tl)
> return tl->mode == INTEL_TIMELINE_ABSOLUTE;
> }
>
> +static inline bool
> +intel_timeline_is_relative(const struct intel_timeline *tl)
> +{
> + return tl->mode != INTEL_TIMELINE_ABSOLUTE;
> +}
> +
> +static inline bool
> +intel_timeline_is_global(const struct intel_timeline *tl)
> +{
> + return tl->mode != INTEL_TIMELINE_CONTEXT;
> +}
> +
> static inline int __intel_timeline_sync_set(struct intel_timeline *tl,
> u64 context, u32 seqno)
> {
> --
> 2.20.1
>
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