On Thu, Dec 10, 2020 at 08:02:40AM +0000, Chris Wilson wrote:
> When we are not using semaphores with a context/engine, we can simply
> reuse the same seqno location across wraps, but we still require each
> timeline to have its own address. For LRC submission, each context is
> prefixed by a per-process HWSP, which provides us with a unique location
> for each context-local timeline. A shared timeline that is common to
> multiple contexts will continue to use a separate page.
>
> This enables us to create position invariant contexts should we feel the
> need to relocate them.
>
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> ---
> .../drm/i915/gt/intel_execlists_submission.c | 37 +++++++++++--------
> 1 file changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> index 8bff0559a6a9..cc1b3509d808 100644
> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> @@ -4749,6 +4749,14 @@ static struct intel_timeline *pinned_timeline(struct intel_context *ce)
> page_unmask_bits(tl));
> }
>
> +static struct intel_timeline *pphwsp_timeline(struct intel_context *ce,
> + struct i915_vma *state)
> +{
> + return __intel_timeline_create(ce->engine->gt, state,
> + I915_GEM_HWS_SEQNO_ADDR |
> + INTEL_TIMELINE_CONTEXT);
> +}
> +
> static int __execlists_context_alloc(struct intel_context *ce,
> struct intel_engine_cs *engine)
> {
> @@ -4779,6 +4787,16 @@ static int __execlists_context_alloc(struct intel_context *ce,
> goto error_deref_obj;
> }
>
> + ring = intel_engine_create_ring(engine, (unsigned long)ce->ring);
> + if (IS_ERR(ring)) {
> + ret = PTR_ERR(ring);
> + goto error_deref_obj;
> + }
> +
> + ret = populate_lr_context(ce, ctx_obj, engine, ring);
> + if (ret)
> + goto error_ring_free;
> +
> if (!page_mask_bits(ce->timeline)) {
> struct intel_timeline *tl;
>
> @@ -4788,29 +4806,18 @@ static int __execlists_context_alloc(struct intel_context *ce,
> */
> if (unlikely(ce->timeline))
> tl = pinned_timeline(ce);
> - else
> + else if (intel_engine_has_semaphores(engine))
> tl = intel_timeline_create(engine->gt);
> + else
> + tl = pphwsp_timeline(ce, vma);
> if (IS_ERR(tl)) {
> ret = PTR_ERR(tl);
> - goto error_deref_obj;
> + goto error_ring_free;
> }
>
> ce->timeline = tl;
> }
>
> - ring = intel_engine_create_ring(engine, (unsigned long)ce->ring);
> - if (IS_ERR(ring)) {
> - ret = PTR_ERR(ring);
> - goto error_deref_obj;
> - }
> -
> - ret = populate_lr_context(ce, ctx_obj, engine, ring);
> - if (ret) {
> - drm_dbg(&engine->i915->drm,
> - "Failed to populate LRC: %d\n", ret);
> - goto error_ring_free;
> - }
> -
> ce->ring = ring;
> ce->state = vma;
>
> --
> 2.20.1
>
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