From 0d7681261453e6f10e0a98e7b744fe4085743291 Mon Sep 17 00:00:00 2001 From: Oscar Mateo Date: Wed, 22 Mar 2017 10:39:50 -0700 Subject: [PATCH] drm/i915/guc: Improve the GuC documentation & comments about proxy submissions While at it, fix a typo (s/ring_lcra/ring_lrca) and improve the naming of one firware interface field (s/ring_tail/submit_element_info, since it can contain more than just the ring tail). No change in functionality. v2: - Remove reference to "unique user" of the GuC (Daniele) - Keep mention to renaming from "GuC context" to "client" (Daniele) Signed-off-by: Oscar Mateo Reviewed-by: Daniele Ceraolo Spurio Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/i915_guc_submission.c | 42 ++++++++++++++-------- drivers/gpu/drm/i915/intel_guc_fwif.h | 4 +-- drivers/gpu/drm/i915/intel_uc.h | 6 ++-- 3 files changed, 33 insertions(+), 19 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c index ab91dac15b5b..e98cb743090f 100644 --- a/drivers/gpu/drm/i915/i915_guc_submission.c +++ b/drivers/gpu/drm/i915/i915_guc_submission.c @@ -30,16 +30,25 @@ /** * DOC: GuC-based command submission * - * i915_guc_client: - * We use the term client to avoid confusion with contexts. A i915_guc_client is - * equivalent to GuC object guc_context_desc. This context descriptor is - * allocated from a pool of 1024 entries. Kernel driver will allocate doorbell - * and workqueue for it. Also the process descriptor (guc_process_desc), which - * is mapped to client space. So the client can write Work Item then ring the - * doorbell. + * GuC client: + * A i915_guc_client refers to a submission path through GuC. Currently, there + * is only one of these (the execbuf_client) and this one is charged with all + * submissions to the GuC. This struct is the owner of a doorbell, a process + * descriptor and a workqueue (all of them inside a single gem object that + * contains all required pages for these elements). * - * To simplify the implementation, we allocate one gem object that contains all - * pages for doorbell, process descriptor and workqueue. + * GuC context descriptor: + * During initialization, the driver allocates a static pool of 1024 such + * descriptors, and shares them with the GuC. + * Currently, there exists a 1:1 mapping between a i915_guc_client and a + * guc_context_desc (via the client's context_index), so effectively only + * one guc_context_desc gets used. This context descriptor lets the GuC know + * about the doorbell, workqueue and process descriptor. Theoretically, it also + * lets the GuC know about our HW contexts (Context ID, etc...), but we actually + * employ a kind of submission where the GuC uses the LRCA sent via the work + * item instead (the single guc_context_desc associated to execbuf client + * contains information about the default kernel context only, but this is + * essentially unused). This is called a "proxy" submission. * * The Scratch registers: * There are 16 MMIO-based registers start from 0xC180. The kernel driver writes @@ -308,10 +317,17 @@ static void guc_ctx_desc_init(struct intel_guc *guc, if (!ce->state) break; /* XXX: continue? */ + /* + * XXX: When this is a GUC_CTX_DESC_ATTR_KERNEL client (proxy + * submission or, in other words, not using a direct submission + * model) the KMD's LRCA is not used for any work submission. + * Instead, the GuC uses the LRCA of the user mode context (see + * guc_wq_item_append below). + */ lrc->context_desc = lower_32_bits(ce->lrc_desc); /* The state page is after PPHWSP */ - lrc->ring_lcra = + lrc->ring_lrca = guc_ggtt_offset(ce->state) + LRC_STATE_PN * PAGE_SIZE; lrc->context_id = (client->ctx_index << GUC_ELC_CTXID_OFFSET) | (guc_engine_id << GUC_ELC_ENGINE_OFFSET); @@ -341,10 +357,6 @@ static void guc_ctx_desc_init(struct intel_guc *guc, desc->wq_addr = gfx_addr + client->wq_offset; desc->wq_size = client->wq_size; - /* - * XXX: Take LRCs from an existing context if this is not an - * IsKMDCreatedContext client - */ desc->desc_private = (uintptr_t)client; } @@ -468,7 +480,7 @@ static void guc_wq_item_append(struct i915_guc_client *client, /* The GuC wants only the low-order word of the context descriptor */ wqi->context_desc = (u32)intel_lr_context_descriptor(rq->ctx, engine); - wqi->ring_tail = tail << WQ_RING_TAIL_SHIFT; + wqi->submit_element_info = tail << WQ_RING_TAIL_SHIFT; wqi->fence_id = rq->global_seqno; } diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h index 3ae8cefa47b3..4edf40fe361f 100644 --- a/drivers/gpu/drm/i915/intel_guc_fwif.h +++ b/drivers/gpu/drm/i915/intel_guc_fwif.h @@ -251,7 +251,7 @@ union guc_doorbell_qw { struct guc_wq_item { u32 header; u32 context_desc; - u32 ring_tail; + u32 submit_element_info; u32 fence_id; } __packed; @@ -278,7 +278,7 @@ struct guc_execlist_context { u32 context_desc; u32 context_id; u32 ring_status; - u32 ring_lcra; + u32 ring_lrca; u32 ring_begin; u32 ring_end; u32 ring_next_free_location; diff --git a/drivers/gpu/drm/i915/intel_uc.h b/drivers/gpu/drm/i915/intel_uc.h index 3ec54a141d2e..65d0b5918661 100644 --- a/drivers/gpu/drm/i915/intel_uc.h +++ b/drivers/gpu/drm/i915/intel_uc.h @@ -34,7 +34,9 @@ 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 specs sometimes refer to this object as a "GuC context", but we use + * the term "client" to avoid confusion with hardware contexts. This + * 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 @@ -44,7 +46,7 @@ struct drm_i915_gem_request; * * 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 + * kmap'd) includes the "process descriptor" 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 -- 2.20.1