On 16/12/15 19:45, yu.dai@xxxxxxxxx wrote:
From: Alex Dai <yu.dai@xxxxxxxxx>
Split GuC work queue space checking from submission and move it to
ring_alloc_request_extras. The reason is that failure in later
i915_add_request() won't be handled. In the case timeout happens,
driver can return early in order to handle the error.
v1: Move wq_reserve_space to ring_reserve_space
v2: Move wq_reserve_space to alloc_request_extras (Chris Wilson)
v3: The work queue head pointer is cached by driver now. So we can
quickly return if space is available.
s/reserve/check/g (Dave Gordon)
v4: Update cached wq head after ring doorbell; check wq space before
ring doorbell in case unexpected error happens; call wq space
check only when GuC submission is enabled. (Dave Gordon)
Signed-off-by: Alex Dai <yu.dai@xxxxxxxxx>
LGTM.
Reviewed-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index ef20071..7554d16 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -247,6 +247,9 @@ static int guc_ring_doorbell(struct i915_guc_client *gc)
db_exc.cookie = 1;
}
+ /* Finally, update the cached copy of the GuC's WQ head */
+ gc->wq_head = desc->head;
+
kunmap_atomic(base);
return ret;
}
@@ -472,28 +475,30 @@ static void guc_fini_ctx_desc(struct intel_guc *guc,
sizeof(desc) * client->ctx_index);
}
-/* Get valid workqueue item and return it back to offset */
-static int guc_get_workqueue_space(struct i915_guc_client *gc, u32 *offset)
+int i915_guc_wq_check_space(struct i915_guc_client *gc)
{
struct guc_process_desc *desc;
void *base;
u32 size = sizeof(struct guc_wq_item);
int ret = -ETIMEDOUT, timeout_counter = 200;
+ if (!gc)
+ return 0;
+
+ /* Quickly return if wq space is available since last time we cache the
+ * head position. */
+ if (CIRC_SPACE(gc->wq_tail, gc->wq_head, gc->wq_size) >= size)
+ return 0;
+
base = kmap_atomic(i915_gem_object_get_page(gc->client_obj, 0));
desc = base + gc->proc_desc_offset;
while (timeout_counter-- > 0) {
- if (CIRC_SPACE(gc->wq_tail, desc->head, gc->wq_size) >= size) {
- *offset = gc->wq_tail;
+ gc->wq_head = desc->head;
- /* advance the tail for next workqueue item */
- gc->wq_tail += size;
- gc->wq_tail &= gc->wq_size - 1;
-
- /* this will break the loop */
- timeout_counter = 0;
+ if (CIRC_SPACE(gc->wq_tail, gc->wq_head, gc->wq_size) >= size) {
ret = 0;
+ break;
}
if (timeout_counter)
@@ -511,12 +516,16 @@ static int guc_add_workqueue_item(struct i915_guc_client *gc,
enum intel_ring_id ring_id = rq->ring->id;
struct guc_wq_item *wqi;
void *base;
- u32 tail, wq_len, wq_off = 0;
- int ret;
+ u32 tail, wq_len, wq_off, space;
+
+ space = CIRC_SPACE(gc->wq_tail, gc->wq_head, gc->wq_size);
+ if (WARN_ON(space < sizeof(struct guc_wq_item)))
+ return -ENOSPC; /* shouldn't happen */
- ret = guc_get_workqueue_space(gc, &wq_off);
- if (ret)
- return ret;
+ /* postincrement WQ tail for next time */
+ wq_off = gc->wq_tail;
+ gc->wq_tail += sizeof(struct guc_wq_item);
+ gc->wq_tail &= gc->wq_size - 1;
/* 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
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index 0e048bf..5cf555d 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -43,6 +43,7 @@ struct i915_guc_client {
uint32_t wq_offset;
uint32_t wq_size;
uint32_t wq_tail;
+ uint32_t wq_head;
/* GuC submission statistics & status */
uint64_t submissions[I915_NUM_RINGS];
@@ -123,5 +124,6 @@ int i915_guc_submit(struct i915_guc_client *client,
struct drm_i915_gem_request *rq);
void i915_guc_submission_disable(struct drm_device *dev);
void i915_guc_submission_fini(struct drm_device *dev);
+int i915_guc_wq_check_space(struct i915_guc_client *client);
#endif
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 272f36f..cd232d2 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -667,6 +667,19 @@ int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request
return ret;
}
+ if (i915.enable_guc_submission) {
+ /*
+ * Check that the GuC has space for the request before
+ * going any further, as the i915_add_request() call
+ * later on mustn't fail ...
+ */
+ struct intel_guc *guc = &request->i915->guc;
+
+ ret = i915_guc_wq_check_space(guc->execbuf_client);
+ if (ret)
+ return ret;
+ }
+
return 0;
}
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