Re: [Intel-gfx] [PATCH 12/26] drm/i915/guc: Implement multi-lrc submission

Matthew Brost
2021-10-13T18:28:52Z

On Fri, Oct 08, 2021 at 10:20:24AM -0700, John Harrison wrote:
> On 10/4/2021 15:06, Matthew Brost wrote:
> > Implement multi-lrc submission via a single workqueue entry and single
> > H2G. The workqueue entry contains an updated tail value for each
> > request, of all the contexts in the multi-lrc submission, and updates
> > these values simultaneously. As such, the tasklet and bypass path have
> > been updated to coalesce requests into a single submission.
> >
> > v2:
> > (John Harrison)
> > - s/wqe/wqi
> > - Use FIELD_PREP macros
> > - Add GEM_BUG_ONs ensures length fits within field
> > - Add comment / white space to intel_guc_write_barrier
> > (Kernel test robot)
> > - Make need_tasklet a static function
> >
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> > ---
> > drivers/gpu/drm/i915/gt/uc/intel_guc.c | 26 ++
> > drivers/gpu/drm/i915/gt/uc/intel_guc.h | 8 +
> > drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 24 +-
> > drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h | 23 +-
> > .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 319 ++++++++++++++++--
> > drivers/gpu/drm/i915/i915_request.h | 8 +
> > 6 files changed, 335 insertions(+), 73 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > index 8f8182bf7c11..7191e8439290 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
> > @@ -756,3 +756,29 @@ void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p)
> > }
> > }
> > }
> > +
> > +void intel_guc_write_barrier(struct intel_guc *guc)
> > +{
> > + struct intel_gt *gt = guc_to_gt(guc);
> > +
> > + if (i915_gem_object_is_lmem(guc->ct.vma->obj)) {
> > + /*
> > + * Ensure intel_uncore_write_fw can be used rather than
> > + * intel_uncore_write.
> > + */
> > + GEM_BUG_ON(guc->send_regs.fw_domains);
> > +
> > + /*
> > + * This register is used by the i915 and GuC for MMIO based
> > + * communication. Once we are in this code CTBs are the only
> > + * method the i915 uses to communicate with the GuC so it is
> > + * safe to write to this register (a value of 0 is NOP for MMIO
> > + * communication). If we ever start mixing CTBs and MMIOs a new
> > + * register will have to be chosen.
> > + */
> Hmm, missed it before but this comment is very CTB centric and the barrier
> function is now being used for parallel submission work queues. Seems like
> an extra comment should be added to cover that case. Just something simple
> about WQ usage is also guaranteed to be post CTB switch over.
>

Sure.

> > + intel_uncore_write_fw(gt->uncore, GEN11_SOFT_SCRATCH(0), 0);
> > + } else {
> > + /* wmb() sufficient for a barrier if in smem */
> > + wmb();
> > + }
> > +}
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > index a9f4ec972bfb..147f39cc0f2f 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> > @@ -46,6 +46,12 @@ struct intel_guc {
> > * submitted until the stalled request is processed.
> > */
> > struct i915_request *stalled_request;
> > + enum {
> > + STALL_NONE,
> > + STALL_REGISTER_CONTEXT,
> > + STALL_MOVE_LRC_TAIL,
> > + STALL_ADD_REQUEST,
> > + } submission_stall_reason;
> > /* intel_guc_recv interrupt related state */
> > /** @irq_lock: protects GuC irq state */
> > @@ -361,4 +367,6 @@ void intel_guc_submission_cancel_requests(struct intel_guc *guc);
> > void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
> > +void intel_guc_write_barrier(struct intel_guc *guc);
> > +
> > #endif
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > index 20c710a74498..10d1878d2826 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> > @@ -377,28 +377,6 @@ static u32 ct_get_next_fence(struct intel_guc_ct *ct)
> > return ++ct->requests.last_fence;
> > }
> > -static void write_barrier(struct intel_guc_ct *ct)
> > -{
> > - struct intel_guc *guc = ct_to_guc(ct);
> > - struct intel_gt *gt = guc_to_gt(guc);
> > -
> > - if (i915_gem_object_is_lmem(guc->ct.vma->obj)) {
> > - GEM_BUG_ON(guc->send_regs.fw_domains);
> > - /*
> > - * This register is used by the i915 and GuC for MMIO based
> > - * communication. Once we are in this code CTBs are the only
> > - * method the i915 uses to communicate with the GuC so it is
> > - * safe to write to this register (a value of 0 is NOP for MMIO
> > - * communication). If we ever start mixing CTBs and MMIOs a new
> > - * register will have to be chosen.
> > - */
> > - intel_uncore_write_fw(gt->uncore, GEN11_SOFT_SCRATCH(0), 0);
> > - } else {
> > - /* wmb() sufficient for a barrier if in smem */
> > - wmb();
> > - }
> > -}
> > -
> > static int ct_write(struct intel_guc_ct *ct,
> > const u32 *action,
> > u32 len /* in dwords */,
> > @@ -468,7 +446,7 @@ static int ct_write(struct intel_guc_ct *ct,
> > * make sure H2G buffer update and LRC tail update (if this triggering a
> > * submission) are visible before updating the descriptor tail
> > */
> > - write_barrier(ct);
> > + intel_guc_write_barrier(ct_to_guc(ct));
> > /* update local copies */
> > ctb->tail = tail;
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > index 0eeb2a9feeed..a00eeddc1449 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_fwif.h
> > @@ -58,19 +58,16 @@
> > #define WQ_STATUS_CMD_ERROR 3
> > #define WQ_STATUS_ENGINE_ID_NOT_USED 4
> > #define WQ_STATUS_SUSPENDED_FROM_RESET 5
> > -#define WQ_TYPE_SHIFT 0
> > -#define WQ_TYPE_BATCH_BUF (0x1 << WQ_TYPE_SHIFT)
> > -#define WQ_TYPE_PSEUDO (0x2 << WQ_TYPE_SHIFT)
> > -#define WQ_TYPE_INORDER (0x3 << WQ_TYPE_SHIFT)
> > -#define WQ_TYPE_NOOP (0x4 << WQ_TYPE_SHIFT)
> > -#define WQ_TARGET_SHIFT 10
> > -#define WQ_LEN_SHIFT 16
> > -#define WQ_NO_WCFLUSH_WAIT (1 << 27)
> > -#define WQ_PRESENT_WORKLOAD (1 << 28)
> > -
> > -#define WQ_RING_TAIL_SHIFT 20
> > -#define WQ_RING_TAIL_MAX 0x7FF /* 2^11 QWords */
> > -#define WQ_RING_TAIL_MASK (WQ_RING_TAIL_MAX << WQ_RING_TAIL_SHIFT)
> > +#define WQ_TYPE_BATCH_BUF 0x1
> > +#define WQ_TYPE_PSEUDO 0x2
> > +#define WQ_TYPE_INORDER 0x3
> > +#define WQ_TYPE_NOOP 0x4
> > +#define WQ_TYPE_MULTI_LRC 0x5
> > +#define WQ_TYPE_MASK GENMASK(7, 0)
> > +#define WQ_LEN_MASK GENMASK(26, 16)
> > +
> > +#define WQ_GUC_ID_MASK GENMASK(15, 0)
> > +#define WQ_RING_TAIL_MASK GENMASK(28, 18)
> Other option for documenting WQ and WQI would be at the top of this block of
> definitions. I believe there is a one line comment of 'work queue item
> header definitions' but none of these defines actually use the WQI
> abbreviation. And some description of what the work queue is, how it is
> used, etc. would be good.
>

Will add something here but again plan on updating the GuC kernel doc
with all the multi-lrc details including WQ / WQI.

> > #define GUC_STAGE_DESC_ATTR_ACTIVE BIT(0)
> > #define GUC_STAGE_DESC_ATTR_PENDING_DB BIT(1)
> > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > index 031b1bf5ba91..1610120e31a1 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -399,6 +399,29 @@ __get_process_desc(struct intel_context *ce)
> > LRC_STATE_OFFSET) / sizeof(u32)));
> > }
> > +static u32 *get_wq_pointer(struct guc_process_desc *desc,
> > + struct intel_context *ce,
> > + u32 wqi_size)
> > +{
> > + /*
> > + * Check for space in work queue. Caching a value of head pointer in
> > + * intel_context structure in order reduce the number accesses to shared
> > + * GPU memory which may be across a PCIe bus.
> > + */
> > +#define AVAILABLE_SPACE \
> > + CIRC_SPACE(ce->parallel.guc.wqi_tail, ce->parallel.guc.wqi_head, WQ_SIZE)
> > + if (wqi_size > AVAILABLE_SPACE) {
> > + ce->parallel.guc.wqi_head = READ_ONCE(desc->head);
> > +
> > + if (wqi_size > AVAILABLE_SPACE)
> > + return NULL;
> > + }
> > +#undef AVAILABLE_SPACE
> > +
> > + return ((u32 *)__get_process_desc(ce)) +
> > + ((WQ_OFFSET + ce->parallel.guc.wqi_tail) / sizeof(u32));
> > +}
> > +
> > static struct guc_lrc_desc *__get_lrc_desc(struct intel_guc *guc, u32 index)
> > {
> > struct guc_lrc_desc *base = guc->lrc_desc_pool_vaddr;
> > @@ -558,10 +581,10 @@ int intel_guc_wait_for_idle(struct intel_guc *guc, long timeout)
> > static int guc_lrc_desc_pin(struct intel_context *ce, bool loop);
> > -static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > +static int __guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > {
> > int err = 0;
> > - struct intel_context *ce = rq->context;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > u32 action[3];
> > int len = 0;
> > u32 g2h_len_dw = 0;
> > @@ -582,26 +605,17 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > GEM_BUG_ON(!atomic_read(&ce->guc_id.ref));
> > GEM_BUG_ON(context_guc_id_invalid(ce));
> > - /*
> > - * Corner case where the GuC firmware was blown away and reloaded while
> > - * this context was pinned.
> > - */
> > - if (unlikely(!lrc_desc_registered(guc, ce->guc_id.id))) {
> > - err = guc_lrc_desc_pin(ce, false);
> > - if (unlikely(err))
> > - return err;
> > - }
> > -
> > spin_lock(&ce->guc_state.lock);
> > /*
> > * The request / context will be run on the hardware when scheduling
> > - * gets enabled in the unblock.
> > + * gets enabled in the unblock. For multi-lrc we still submit the
> > + * context to move the LRC tails.
> > */
> > - if (unlikely(context_blocked(ce)))
> > + if (unlikely(context_blocked(ce) && !intel_context_is_parent(ce)))
> > goto out;
> > - enabled = context_enabled(ce);
> > + enabled = context_enabled(ce) || context_blocked(ce);
> > if (!enabled) {
> > action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
> > @@ -620,6 +634,18 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > trace_intel_context_sched_enable(ce);
> > atomic_inc(&guc->outstanding_submission_g2h);
> > set_context_enabled(ce);
> > +
> > + /*
> > + * Without multi-lrc KMD does the submission step (moving the
> > + * lrc tail) so enabling scheduling is sufficient to submit the
> > + * context. This isn't the case in multi-lrc submission as the
> > + * GuC needs to move the tails, hence the need for another H2G
> > + * to submit a multi-lrc context after enabling scheduling.
> > + */
> > + if (intel_context_is_parent(ce)) {
> > + action[0] = INTEL_GUC_ACTION_SCHED_CONTEXT;
> > + err = intel_guc_send_nb(guc, action, len - 1, 0);
> > + }
> > } else if (!enabled) {
> > clr_context_pending_enable(ce);
> > intel_context_put(ce);
> > @@ -632,6 +658,18 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > return err;
> > }
> > +static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > +{
> > + int ret = __guc_add_request(guc, rq);
> > +
> > + if (unlikely(ret == -EBUSY)) {
> > + guc->stalled_request = rq;
> > + guc->submission_stall_reason = STALL_ADD_REQUEST;
> > + }
> > +
> > + return ret;
> > +}
> > +
> > static inline void guc_set_lrc_tail(struct i915_request *rq)
> > {
> > rq->context->lrc_reg_state[CTX_RING_TAIL] =
> > @@ -643,6 +681,134 @@ static inline int rq_prio(const struct i915_request *rq)
> > return rq->sched.attr.priority;
> > }
> > +static bool is_multi_lrc_rq(struct i915_request *rq)
> > +{
> > + return intel_context_is_child(rq->context) ||
> > + intel_context_is_parent(rq->context);
> > +}
> > +
> > +static bool can_merge_rq(struct i915_request *rq,
> > + struct i915_request *last)
> > +{
> > + return request_to_scheduling_context(rq) ==
> > + request_to_scheduling_context(last);
> > +}
> > +
> > +static u32 wq_space_until_wrap(struct intel_context *ce)
> > +{
> > + return (WQ_SIZE - ce->parallel.guc.wqi_tail);
> > +}
> > +
> > +static void write_wqi(struct guc_process_desc *desc,
> > + struct intel_context *ce,
> > + u32 wqi_size)
> > +{
> > + /*
> > + * Ensure WQI are visible before updating tail
> > + */
> > + intel_guc_write_barrier(ce_to_guc(ce));
> > +
> > + ce->parallel.guc.wqi_tail = (ce->parallel.guc.wqi_tail + wqi_size) &
> > + (WQ_SIZE - 1);
> This relies on WQ_SIZE being a power of two, right? Is it possible to add a
> BUILD_BUG_ON to ensure that?
>

Yep.

> > + WRITE_ONCE(desc->tail, ce->parallel.guc.wqi_tail);
> > +}
> > +
> > +static int guc_wq_noop_append(struct intel_context *ce)
> > +{
> > + struct guc_process_desc *desc = __get_process_desc(ce);
> > + u32 *wqi = get_wq_pointer(desc, ce, wq_space_until_wrap(ce));
> > + u32 len_dw = wq_space_until_wrap(ce) / sizeof(u32) - 1;
> > +
> > + if (!wqi)
> > + return -EBUSY;
> > +
> > + GEM_BUG_ON(!FIELD_FIT(WQ_LEN_MASK, len_dw));
> > +
> > + *wqi = FIELD_PREP(WQ_TYPE_MASK, WQ_TYPE_NOOP) |
> > + FIELD_PREP(WQ_LEN_MASK, len_dw);
> > + ce->parallel.guc.wqi_tail = 0;
> > +
> > + return 0;
> > +}
> > +
> > +static int __guc_wq_item_append(struct i915_request *rq)
> > +{
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > + struct intel_context *child;
> > + struct guc_process_desc *desc = __get_process_desc(ce);
> > + unsigned int wqi_size = (ce->parallel.number_children + 4) *
> > + sizeof(u32);
> > + u32 *wqi;
> > + u32 len_dw = (wqi_size / sizeof(u32)) - 1;
> > + int ret;
> > +
> > + /* Ensure context is in correct state updating work queue */
> > + GEM_BUG_ON(!atomic_read(&ce->guc_id.ref));
> > + GEM_BUG_ON(context_guc_id_invalid(ce));
> > + GEM_BUG_ON(context_wait_for_deregister_to_register(ce));
> > + GEM_BUG_ON(!lrc_desc_registered(ce_to_guc(ce), ce->guc_id.id));
> > +
> > + /* Insert NOOP if this work queue item will wrap the tail pointer. */
> > + if (wqi_size > wq_space_until_wrap(ce)) {
> > + ret = guc_wq_noop_append(ce);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + wqi = get_wq_pointer(desc, ce, wqi_size);
> > + if (!wqi)
> > + return -EBUSY;
> > +
> > + GEM_BUG_ON(!FIELD_FIT(WQ_LEN_MASK, len_dw));
> > +
> > + *wqi++ = FIELD_PREP(WQ_TYPE_MASK, WQ_TYPE_MULTI_LRC) |
> > + FIELD_PREP(WQ_LEN_MASK, len_dw);
> > + *wqi++ = ce->lrc.lrca;
> > + *wqi++ = FIELD_PREP(WQ_GUC_ID_MASK, ce->guc_id.id) |
> > + FIELD_PREP(WQ_RING_TAIL_MASK, ce->ring->tail / sizeof(u64));
> > + *wqi++ = 0; /* fence_id */
> > + for_each_child(ce, child)
> > + *wqi++ = child->ring->tail / sizeof(u64);
> > +
> > + write_wqi(desc, ce, wqi_size);
> > +
> > + return 0;
> > +}
> > +
> > +static int guc_wq_item_append(struct intel_guc *guc,
> > + struct i915_request *rq)
> > +{
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > + int ret = 0;
> > +
> > + if (likely(!intel_context_is_banned(ce))) {
> > + ret = __guc_wq_item_append(rq);
> > +
> > + if (unlikely(ret == -EBUSY)) {
> > + guc->stalled_request = rq;
> > + guc->submission_stall_reason = STALL_MOVE_LRC_TAIL;
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static bool multi_lrc_submit(struct i915_request *rq)
> > +{
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > +
> > + intel_ring_set_tail(rq->ring, rq->tail);
> > +
> > + /*
> > + * We expect the front end (execbuf IOCTL) to set this flag on the last
> > + * request generated from a multi-BB submission. This indicates to the
> > + * backend (GuC interface) that we should submit this context thus
> > + * submitting all the requests generated in parallel.
> > + */
> > + return test_bit(I915_FENCE_FLAG_SUBMIT_PARALLEL, &rq->fence.flags) ||
> FYI: Apparently the test_bit/set_bit/etc helpers are intended for use on
> arbitrary sized bitfields. As in, they do all sorts of complicated atomic
> operations to work on 164 bit words and such like. For single word flags,
> the guidance is to just use 'if(word & BIT(bit))' instead.
>

I get that but currently everywhere in the code uses
set_bit/clear_bit/test_bit on the rq->fence.flags. IMO is better to
stick to that convention for now rip of all of these helpers in a single
patch later. I'd rather not have a hodgepodge of styles in the code.

I can an AR to clean up rq->fence.flags everywhere in the code in a
follow up.

Matt

> John.
>
> > + intel_context_is_banned(ce);
> > +}
> > +
> > static int guc_dequeue_one_context(struct intel_guc *guc)
> > {
> > struct i915_sched_engine * const sched_engine = guc->sched_engine;
> > @@ -656,7 +822,17 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> > if (guc->stalled_request) {
> > submit = true;
> > last = guc->stalled_request;
> > - goto resubmit;
> > +
> > + switch (guc->submission_stall_reason) {
> > + case STALL_REGISTER_CONTEXT:
> > + goto register_context;
> > + case STALL_MOVE_LRC_TAIL:
> > + goto move_lrc_tail;
> > + case STALL_ADD_REQUEST:
> > + goto add_request;
> > + default:
> > + MISSING_CASE(guc->submission_stall_reason);
> > + }
> > }
> > while ((rb = rb_first_cached(&sched_engine->queue))) {
> > @@ -664,8 +840,8 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> > struct i915_request *rq, *rn;
> > priolist_for_each_request_consume(rq, rn, p) {
> > - if (last && rq->context != last->context)
> > - goto done;
> > + if (last && !can_merge_rq(rq, last))
> > + goto register_context;
> > list_del_init(&rq->sched.link);
> > @@ -673,33 +849,84 @@ static int guc_dequeue_one_context(struct intel_guc *guc)
> > trace_i915_request_in(rq, 0);
> > last = rq;
> > - submit = true;
> > +
> > + if (is_multi_lrc_rq(rq)) {
> > + /*
> > + * We need to coalesce all multi-lrc requests in
> > + * a relationship into a single H2G. We are
> > + * guaranteed that all of these requests will be
> > + * submitted sequentially.
> > + */
> > + if (multi_lrc_submit(rq)) {
> > + submit = true;
> > + goto register_context;
> > + }
> > + } else {
> > + submit = true;
> > + }
> > }
> > rb_erase_cached(&p->node, &sched_engine->queue);
> > i915_priolist_free(p);
> > }
> > -done:
> > +
> > +register_context:
> > if (submit) {
> > - guc_set_lrc_tail(last);
> > -resubmit:
> > + struct intel_context *ce = request_to_scheduling_context(last);
> > +
> > + if (unlikely(!lrc_desc_registered(guc, ce->guc_id.id) &&
> > + !intel_context_is_banned(ce))) {
> > + ret = guc_lrc_desc_pin(ce, false);
> > + if (unlikely(ret == -EPIPE)) {
> > + goto deadlk;
> > + } else if (ret == -EBUSY) {
> > + guc->stalled_request = last;
> > + guc->submission_stall_reason =
> > + STALL_REGISTER_CONTEXT;
> > + goto schedule_tasklet;
> > + } else if (ret != 0) {
> > + GEM_WARN_ON(ret); /* Unexpected */
> > + goto deadlk;
> > + }
> > + }
> > +
> > +move_lrc_tail:
> > + if (is_multi_lrc_rq(last)) {
> > + ret = guc_wq_item_append(guc, last);
> > + if (ret == -EBUSY) {
> > + goto schedule_tasklet;
> > + } else if (ret != 0) {
> > + GEM_WARN_ON(ret); /* Unexpected */
> > + goto deadlk;
> > + }
> > + } else {
> > + guc_set_lrc_tail(last);
> > + }
> > +
> > +add_request:
> > ret = guc_add_request(guc, last);
> > - if (unlikely(ret == -EPIPE))
> > + if (unlikely(ret == -EPIPE)) {
> > + goto deadlk;
> > + } else if (ret == -EBUSY) {
> > + goto schedule_tasklet;
> > + } else if (ret != 0) {
> > + GEM_WARN_ON(ret); /* Unexpected */
> > goto deadlk;
> > - else if (ret == -EBUSY) {
> > - tasklet_schedule(&sched_engine->tasklet);
> > - guc->stalled_request = last;
> > - return false;
> > }
> > }
> > guc->stalled_request = NULL;
> > + guc->submission_stall_reason = STALL_NONE;
> > return submit;
> > deadlk:
> > sched_engine->tasklet.callback = NULL;
> > tasklet_disable_nosync(&sched_engine->tasklet);
> > return false;
> > +
> > +schedule_tasklet:
> > + tasklet_schedule(&sched_engine->tasklet);
> > + return false;
> > }
> > static void guc_submission_tasklet(struct tasklet_struct *t)
> > @@ -1255,10 +1482,16 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> > trace_i915_request_in(rq, 0);
> > - guc_set_lrc_tail(rq);
> > - ret = guc_add_request(guc, rq);
> > - if (ret == -EBUSY)
> > - guc->stalled_request = rq;
> > + if (is_multi_lrc_rq(rq)) {
> > + if (multi_lrc_submit(rq)) {
> > + ret = guc_wq_item_append(guc, rq);
> > + if (!ret)
> > + ret = guc_add_request(guc, rq);
> > + }
> > + } else {
> > + guc_set_lrc_tail(rq);
> > + ret = guc_add_request(guc, rq);
> > + }
> > if (unlikely(ret == -EPIPE))
> > disable_submission(guc);
> > @@ -1266,6 +1499,16 @@ static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> > return ret;
> > }
> > +static bool need_tasklet(struct intel_guc *guc, struct i915_request *rq)
> > +{
> > + struct i915_sched_engine *sched_engine = rq->engine->sched_engine;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > +
> > + return submission_disabled(guc) || guc->stalled_request ||
> > + !i915_sched_engine_is_empty(sched_engine) ||
> > + !lrc_desc_registered(guc, ce->guc_id.id);
> > +}
> > +
> > static void guc_submit_request(struct i915_request *rq)
> > {
> > struct i915_sched_engine *sched_engine = rq->engine->sched_engine;
> > @@ -1275,8 +1518,7 @@ static void guc_submit_request(struct i915_request *rq)
> > /* Will be called from irq-context when using foreign fences. */
> > spin_lock_irqsave(&sched_engine->lock, flags);
> > - if (submission_disabled(guc) || guc->stalled_request ||
> > - !i915_sched_engine_is_empty(sched_engine))
> > + if (need_tasklet(guc, rq))
> > queue_request(sched_engine, rq, rq_prio(rq));
> > else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> > tasklet_hi_schedule(&sched_engine->tasklet);
> > @@ -2258,9 +2500,10 @@ static inline bool new_guc_prio_higher(u8 old_guc_prio, u8 new_guc_prio)
> > static void add_to_context(struct i915_request *rq)
> > {
> > - struct intel_context *ce = rq->context;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > u8 new_guc_prio = map_i915_prio_to_guc_prio(rq_prio(rq));
> > + GEM_BUG_ON(intel_context_is_child(ce));
> > GEM_BUG_ON(rq->guc_prio == GUC_PRIO_FINI);
> > spin_lock(&ce->guc_state.lock);
> > @@ -2293,7 +2536,9 @@ static void guc_prio_fini(struct i915_request *rq, struct intel_context *ce)
> > static void remove_from_context(struct i915_request *rq)
> > {
> > - struct intel_context *ce = rq->context;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > +
> > + GEM_BUG_ON(intel_context_is_child(ce));
> > spin_lock_irq(&ce->guc_state.lock);
> > @@ -2712,7 +2957,7 @@ static void guc_init_breadcrumbs(struct intel_engine_cs *engine)
> > static void guc_bump_inflight_request_prio(struct i915_request *rq,
> > int prio)
> > {
> > - struct intel_context *ce = rq->context;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > u8 new_guc_prio = map_i915_prio_to_guc_prio(prio);
> > /* Short circuit function */
> > @@ -2735,7 +2980,7 @@ static void guc_bump_inflight_request_prio(struct i915_request *rq,
> > static void guc_retire_inflight_request_prio(struct i915_request *rq)
> > {
> > - struct intel_context *ce = rq->context;
> > + struct intel_context *ce = request_to_scheduling_context(rq);
> > spin_lock(&ce->guc_state.lock);
> > guc_prio_fini(rq, ce);
> > diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
> > index 7bd9ed20623e..8950785e55d6 100644
> > --- a/drivers/gpu/drm/i915/i915_request.h
> > +++ b/drivers/gpu/drm/i915/i915_request.h
> > @@ -139,6 +139,14 @@ enum {
> > * the GPU. Here we track such boost requests on a per-request basis.
> > */
> > I915_FENCE_FLAG_BOOST,
> > +
> > + /*
> > + * I915_FENCE_FLAG_SUBMIT_PARALLEL - request with a context in a
> > + * parent-child relationship (parallel submission, multi-lrc) should
> > + * trigger a submission to the GuC rather than just moving the context
> > + * tail.
> > + */
> > + I915_FENCE_FLAG_SUBMIT_PARALLEL,
> > };
> > /**
>