Tidying up guc_init_proc_desc() and adding commentary to the client
structure after the recent change in GuC page mapping strategy.
Signed-off-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_guc_submission.c | 38 ++++++++++++++----------------
drivers/gpu/drm/i915/intel_guc.h | 23 ++++++++++++++++++
2 files changed, 41 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 4718b7a..d40c13f 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -358,12 +358,14 @@ static void guc_init_proc_desc(struct intel_guc *guc,
static void guc_init_ctx_desc(struct intel_guc *guc,
struct i915_guc_client *client)
{
+ struct drm_i915_gem_object *client_obj = client->client_obj;
struct drm_i915_private *dev_priv = guc_to_i915(guc);
struct intel_engine_cs *engine;
struct intel_context *ctx = client->owner;
struct guc_context_desc desc;
struct sg_table *sg;
enum intel_engine_id id;
+ u32 gfx_addr;
memset(&desc, 0, sizeof(desc));
@@ -392,16 +394,17 @@ static void guc_init_ctx_desc(struct intel_guc *guc,
lrc->context_desc = (u32)ctx_desc;
/* The state page is after PPHWSP */
- lrc->ring_lcra = i915_gem_obj_ggtt_offset(obj) +
- LRC_STATE_PN * PAGE_SIZE;
+ gfx_addr = i915_gem_obj_ggtt_offset(obj);
+ lrc->ring_lcra = gfx_addr + LRC_STATE_PN * PAGE_SIZE;
lrc->context_id = (client->ctx_index << GUC_ELC_CTXID_OFFSET) |
(engine->guc_id << GUC_ELC_ENGINE_OFFSET);
obj = ctx->engine[id].ringbuf->obj;
+ gfx_addr = i915_gem_obj_ggtt_offset(obj);
- lrc->ring_begin = i915_gem_obj_ggtt_offset(obj);
- lrc->ring_end = lrc->ring_begin + obj->base.size - 1;
- lrc->ring_next_free_location = lrc->ring_begin;
+ lrc->ring_begin = gfx_addr;
+ lrc->ring_end = gfx_addr + obj->base.size - 1;
+ lrc->ring_next_free_location = gfx_addr;
lrc->ring_current_tail_pointer_value = 0;
desc.engines_used |= (1 << engine->guc_id);
@@ -410,22 +413,17 @@ static void guc_init_ctx_desc(struct intel_guc *guc,
WARN_ON(desc.engines_used == 0);
/*
- * The CPU address is only needed at certain points, so kmap_atomic on
- * demand instead of storing it in the ctx descriptor.
- * XXX: May make debug easier to have it mapped
+ * The doorbell, process descriptor, and workqueue are all parts
+ * of the client object, which the GuC will reference via the GGTT
*/
- desc.db_trigger_cpu = 0;
- desc.db_trigger_uk = client->doorbell_offset +
- i915_gem_obj_ggtt_offset(client->client_obj);
- desc.db_trigger_phy = client->doorbell_offset +
- sg_dma_address(client->client_obj->pages->sgl);
-
- desc.process_desc = client->proc_desc_offset +
- i915_gem_obj_ggtt_offset(client->client_obj);
-
- desc.wq_addr = client->wq_offset +
- i915_gem_obj_ggtt_offset(client->client_obj);
-
+ gfx_addr = i915_gem_obj_ggtt_offset(client_obj);
+ desc.db_trigger_phy = sg_dma_address(client_obj->pages->sgl) +
+ client->doorbell_offset;
+ desc.db_trigger_cpu = (uintptr_t)client->client_base +
+ client->doorbell_offset;
+ 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;
/*
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index 19ca593..9d79c4c 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -29,6 +29,29 @@
struct drm_i915_gem_request;
+/*
+ * This structure primarily describes the GEM object shared with the GuC.
+ * The GEM object is held for the entire lifetime of our interaction with
+ * the GuC, being allocated before the GuC is loaded with its firmware.
+ * Because there's no way to update the address used by the GuC after
+ * initialisation, the shared object must stay pinned into the GGTT as
+ * long as the GuC is in use. We also keep the first page (only) mapped
+ * into kernel address space, as it includes shared data that must be
+ * updated on every request submission.
+ *
+ * The single GEM object described here is actually made up of several
+ * separate areas, as far as the GuC is concerned. The first page (kept
+ * kmap'd) includes the "process decriptor" which holds sequence data for
+ * the doorbell, and one cacheline which actually *is* the doorbell; a
+ * write to this will "ring the doorbell" (i.e. send an interrupt to the
+ * GuC). The subsequent pages of the client object constitute the work
+ * queue (a circular array of work items), again described in the process
+ * descriptor. Work queue pages are mapped momentarily as required.
+ *
+ * Finally, we also keep a few statistics here, including the number of
+ * submissions to each engine, and a record of the last submission failure
+ * (if any).
+ */
struct i915_guc_client {
struct drm_i915_gem_object *client_obj;
void *client_base; /* first page (only) of above */
--
1.9.1
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