[Intel-gfx] [PATCH v3 4/5] drm/i915/guc: Cleanup adding GuC work items
Daniele Ceraolo Spurio
daniele.ceraolospurio at intel.com
Mon Sep 18 16:10:30 UTC 2017
On 18/09/17 02:25, Michał Winiarski wrote:
> We can just operate on the wq_tail directly (in the process descriptor).
> This allows us to remove the duplicated tail from the client. While I'm
> here let's also remove the constants kept in the client and document our
> locking requirements. This causes a small change in one of GuC debugfs
> files. We're no longer reporting constant values (which I don't think
> is a problem), but we're also no longer reporting the tail (does anyone
> care?).
>
> v2: Update tail after wqi contents. (Chris)
> v3: Really update tail after wqi contents.
>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Oscar Mateo <oscar.mateo at intel.com>
> Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 2 --
> drivers/gpu/drm/i915/i915_guc_submission.c | 37 +++++++++++++-----------------
> drivers/gpu/drm/i915/intel_uc.h | 4 ----
> 3 files changed, 16 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 46ac6091772e..2518bdf95eef 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2447,8 +2447,6 @@ static void i915_guc_client_info(struct seq_file *m,
> client->priority, client->stage_id, client->proc_desc_offset);
> seq_printf(m, "\tDoorbell id %d, offset: 0x%lx\n",
> client->doorbell_id, client->doorbell_offset);
> - seq_printf(m, "\tWQ size %d, offset: 0x%x, tail %d\n",
> - client->wq_size, client->wq_offset, client->wq_tail);
>
> for_each_engine(engine, dev_priv, id) {
> u64 submissions = client->submissions[id];
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index 16ce570a0b74..18fefc11b8d7 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -305,7 +305,7 @@ static void guc_proc_desc_init(struct intel_guc *guc,
> desc->db_base_addr = 0;
>
> desc->stage_id = client->stage_id;
> - desc->wq_size_bytes = client->wq_size;
> + desc->wq_size_bytes = GUC_WQ_SIZE;
> desc->wq_status = WQ_STATUS_ACTIVE;
> desc->priority = client->priority;
> }
> @@ -390,8 +390,8 @@ static void guc_stage_desc_init(struct intel_guc *guc,
> desc->db_trigger_cpu = (uintptr_t)__get_doorbell(client);
> desc->db_trigger_uk = gfx_addr + client->doorbell_offset;
> desc->process_desc = gfx_addr + client->proc_desc_offset;
> - desc->wq_addr = gfx_addr + client->wq_offset;
> - desc->wq_size = client->wq_size;
> + desc->wq_addr = gfx_addr + GUC_DB_SIZE;
> + desc->wq_size = GUC_WQ_SIZE;
>
> desc->desc_private = (uintptr_t)client;
> }
> @@ -416,14 +416,12 @@ static void guc_wq_item_append(struct i915_guc_client *client,
> struct i915_gem_context *ctx = rq->ctx;
> struct guc_process_desc *desc = __get_process_desc(client);
> struct guc_wq_item *wqi;
> - u32 freespace, tail, wq_off;
> + u32 ring_tail, wq_off;
>
> - /* Free space is guaranteed */
> - freespace = CIRC_SPACE(client->wq_tail, desc->head, client->wq_size);
> - GEM_BUG_ON(freespace < wqi_size);
> + lockdep_assert_held(&client->wq_lock);
>
> - tail = intel_ring_set_tail(rq->ring, rq->tail) / sizeof(u64);
> - GEM_BUG_ON(tail > WQ_RING_TAIL_MAX);
> + ring_tail = intel_ring_set_tail(rq->ring, rq->tail) / sizeof(u64);
> + GEM_BUG_ON(ring_tail > WQ_RING_TAIL_MAX);
>
> /* For now workqueue item is 4 DWs; workqueue buffer is 2 pages. So we
> * should not have the case where structure wqi is across page, neither
> @@ -434,11 +432,11 @@ static void guc_wq_item_append(struct i915_guc_client *client,
> */
> BUILD_BUG_ON(wqi_size != 16);
>
> - /* postincrement WQ tail for next time */
> - wq_off = client->wq_tail;
> + /* Free space is guaranteed. */
> + wq_off = READ_ONCE(desc->tail);
> + GEM_BUG_ON(CIRC_SPACE(wq_off, READ_ONCE(desc->head),
> + GUC_WQ_SIZE) < wqi_size);
> GEM_BUG_ON(wq_off & (wqi_size - 1));
> - client->wq_tail += wqi_size;
> - client->wq_tail &= client->wq_size - 1;
>
> /* WQ starts from the page after doorbell / process_desc */
> wqi = client->vaddr + wq_off + GUC_DB_SIZE;
> @@ -451,8 +449,11 @@ static void guc_wq_item_append(struct i915_guc_client *client,
>
> wqi->context_desc = lower_32_bits(intel_lr_context_descriptor(ctx, engine));
>
> - wqi->submit_element_info = tail << WQ_RING_TAIL_SHIFT;
> + wqi->submit_element_info = ring_tail << WQ_RING_TAIL_SHIFT;
> wqi->fence_id = rq->global_seqno;
> +
> + /* Postincrement WQ tail for next time. */
Apologies for the late comment, just a nitpick: by updating desc->tail
here we're making the update visible to GuC, we're not doing something
for next SW iteration. I believe the comment was used to refer to the SW
tracker (client->wq_tail) that is now gone so we could reword/drop it.
Daniele
> + WRITE_ONCE(desc->tail, (wq_off + wqi_size) & (GUC_WQ_SIZE - 1));
> }
>
> static void guc_reset_wq(struct i915_guc_client *client)
> @@ -461,18 +462,14 @@ static void guc_reset_wq(struct i915_guc_client *client)
>
> desc->head = 0;
> desc->tail = 0;
> -
> - client->wq_tail = 0;
> }
>
> static void guc_ring_doorbell(struct i915_guc_client *client)
> {
> - struct guc_process_desc *desc = __get_process_desc(client);
> struct guc_doorbell_info *db;
> u32 cookie;
>
> - /* Update the tail so it is visible to GuC */
> - desc->tail = client->wq_tail;
> + lockdep_assert_held(&client->wq_lock);
>
> /* pointer of current doorbell cacheline */
> db = __get_doorbell(client);
> @@ -813,8 +810,6 @@ guc_client_alloc(struct drm_i915_private *dev_priv,
> client->engines = engines;
> client->priority = priority;
> client->doorbell_id = GUC_DOORBELL_INVALID;
> - client->wq_offset = GUC_DB_SIZE;
> - client->wq_size = GUC_WQ_SIZE;
> spin_lock_init(&client->wq_lock);
>
> ret = ida_simple_get(&guc->stage_ids, 0, GUC_MAX_STAGE_DESCRIPTORS,
> diff --git a/drivers/gpu/drm/i915/intel_uc.h b/drivers/gpu/drm/i915/intel_uc.h
> index f505dcccd613..7703c9ad6511 100644
> --- a/drivers/gpu/drm/i915/intel_uc.h
> +++ b/drivers/gpu/drm/i915/intel_uc.h
> @@ -68,10 +68,6 @@ struct i915_guc_client {
> unsigned long doorbell_offset;
>
> spinlock_t wq_lock;
> - uint32_t wq_offset;
> - uint32_t wq_size;
> - uint32_t wq_tail;
> -
> /* Per-engine counts of GuC submissions */
> uint64_t submissions[I915_NUM_ENGINES];
> };
>
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