Add GuC kernel doc for all structures added thus far for GuC submission and update the main GuC submission section with the new interface details.
v2: - Drop guc_active.lock DOC v3: (Daniele) - Fixup a few kernel doc comments
Signed-off-by: Matthew Brost matthew.brost@intel.com --- drivers/gpu/drm/i915/gt/intel_context_types.h | 44 +++++--- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 19 +++- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 101 ++++++++++++++---- drivers/gpu/drm/i915/i915_request.h | 18 ++-- 4 files changed, 132 insertions(+), 50 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h index 5285d660eacf..920ed92f4382 100644 --- a/drivers/gpu/drm/i915/gt/intel_context_types.h +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h @@ -156,40 +156,52 @@ struct intel_context { u8 wa_bb_page; /* if set, page num reserved for context workarounds */
struct { - /** lock: protects everything in guc_state */ + /** @lock: protects everything in guc_state */ spinlock_t lock; /** - * sched_state: scheduling state of this context using GuC + * @sched_state: scheduling state of this context using GuC * submission */ u32 sched_state; /* - * fences: maintains of list of requests that have a submit - * fence related to GuC submission + * @fences: maintains a list of requests are currently being + * fenced until a GuC operation completes */ struct list_head fences; - /* GuC context blocked fence */ + /** + * @blocked: fence used to signal when the blocking of a + * contexts submissions is complete. + */ struct i915_sw_fence blocked; - /* GuC committed requests */ + /** @number_committed_requests: number of committed requests */ int number_committed_requests; - /** requests: active requests on this context */ + /** @requests: list of active requests on this context */ struct list_head requests; - /* - * GuC priority management - */ + /** @prio: the contexts current guc priority */ u8 prio; + /** + * @prio_count: a counter of the number requests inflight in + * each priority bucket + */ u32 prio_count[GUC_CLIENT_PRIORITY_NUM]; } guc_state;
struct { - /* GuC LRC descriptor ID */ + /** + * @id: unique handle which is used to communicate information + * with the GuC about this context, protected by + * guc->contexts_lock + */ u16 id; - - /* GuC LRC descriptor reference count */ + /** + * @ref: the number of references to the guc_id, when + * transitioning in and out of zero protected by + * guc->contexts_lock + */ atomic_t ref; - - /* - * GuC ID link - in list when unpinned but guc_id still valid in GuC + /** + * @link: in guc->guc_id_list when the guc_id has no refs but is + * still valid, protected by guc->contexts_lock */ struct list_head link; } guc_id; diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 2e27fe59786b..112dd29a63fe 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -41,6 +41,10 @@ struct intel_guc { spinlock_t irq_lock; unsigned int msg_enabled_mask;
+ /** + * @outstanding_submission_g2h: number of outstanding G2H related to GuC + * submission, used to determine if the GT is idle + */ atomic_t outstanding_submission_g2h;
struct { @@ -49,12 +53,16 @@ struct intel_guc { void (*disable)(struct intel_guc *guc); } interrupts;
- /* - * contexts_lock protects the pool of free guc ids and a linked list of - * guc ids available to be stolen + /** + * @contexts_lock: protects guc_ids, guc_id_list, ce->guc_id.id, and + * ce->guc_id.ref when transitioning in and out of zero */ spinlock_t contexts_lock; + /** @guc_ids: used to allocate new guc_ids */ struct ida guc_ids; + /** + * @guc_id_list: list of intel_context with valid guc_ids but no refs + */ struct list_head guc_id_list;
bool submission_supported; @@ -70,7 +78,10 @@ struct intel_guc { struct i915_vma *lrc_desc_pool; void *lrc_desc_pool_vaddr;
- /* guc_id to intel_context lookup */ + /** + * @context_lookup: used to resolve intel_context from guc_id, if a + * context is present in this structure it is registered with the GuC + */ struct xarray context_lookup;
/* Control params for fw initialization */ 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 eb884b48f4b8..3fe45eca95ff 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -28,21 +28,6 @@ /** * DOC: GuC-based command submission * - * IMPORTANT NOTE: GuC submission is currently not supported in i915. The GuC - * firmware is moving to an updated submission interface and we plan to - * turn submission back on when that lands. The below documentation (and related - * code) matches the old submission model and will be updated as part of the - * upgrade to the new flow. - * - * GuC stage descriptor: - * During initialization, the driver allocates a static pool of 1024 such - * descriptors, and shares them with the GuC. Currently, we only use one - * descriptor. This stage descriptor lets the GuC know about the 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. This is called - * a "proxy" submission. - * * The Scratch registers: * There are 16 MMIO-based registers start from 0xC180. The kernel driver writes * a value to the action register (SOFT_SCRATCH_0) along with any data. It then @@ -51,14 +36,86 @@ * processes the request. The kernel driver polls waiting for this update and * then proceeds. * - * Work Items: - * There are several types of work items that the host may place into a - * workqueue, each with its own requirements and limitations. Currently only - * WQ_TYPE_INORDER is needed to support legacy submission via GuC, which - * represents in-order queue. The kernel driver packs ring tail pointer and an - * ELSP context descriptor dword into Work Item. - * See guc_add_request() + * Command Transport buffers (CTBs): + * Covered in detail in other sections but CTBs (host-to-guc, H2G, guc-to-host + * G2H) are a message interface between the i915 and GuC used to controls + * submissions. + * + * Context registration: + * Before a context can be submitted it must be registered with the GuC via a + * H2G. A unique guc_id is associated with each context. The context is either + * registered at request creation time (normal operation) or at submission time + * (abnormal operation, e.g. after a reset). + * + * Context submission: + * The i915 updates the LRC tail value in memory. The i915 must enable the + * scheduling of the context within the GuC for the GuC to actually consider it. + * Therefore, the first time a disabled context is submitted we use a schedule + * enable H2G, while follow upsubmissions are done via the context submit H2G, + * which informs the GuC that a previously enabled context has new work + * available. + * + * Context unpin: + * To unpin a context a H2G is used to disable scheduling and when the + * corresponding G2H returns indicating the scheduling disable operation has + * completed it is safe to unpin the context. While a disable is in flight it + * isn't safe to resubmit the context so a fence is used to stall all future + * requests until the G2H is returned. + * + * Context deregistration: + * Before a context can be destroyed or if we steal its guc_id we must + * deregister the context with the GuC via H2G. If stealing the guc_id it isn't + * safe to submit anything to this guc_id until the deregister completes so a + * fence is used to stall all requests associated with this guc_ids until the + * corresponding G2H returns indicating the guc_id has been deregistered. + * + * guc_ids: + * Unique number associated with private GuC context data passed in during + * context registration / submission / deregistration. 64k available. Simple ida + * is used for allocation. + * + * Stealing guc_ids: + * If no guc_ids are available they can be stolen from another context at + * request creation time if that context is unpinned. If a guc_id can't be found + * we punt this problem to the user as we believe this is near impossible to hit + * during normal use cases. + * + * Locking: + * In the GuC submission code we have 3 basic spin locks which protect + * everything. Details about each below. + * + * sched_engine->lock + * This is the submission lock for all contexts that share a i915 schedule + * engine (sched_engine), thus only 1 context which share a sched_engine can be + * submitting at a time. Currently only 1 sched_engine used for all of GuC + * submission but that could change in the future. + * + * guc->contexts_lock + * Protects guc_id allocation. Global lock i.e. Only 1 context that uses GuC + * submission can hold this at a time. + * + * ce->guc_state.lock + * Protects everything under ce->guc_state. Ensures that a context is in the + * correct state before issuing a H2G. e.g. We don't issue a schedule disable + * on disabled context (bad idea), we don't issue schedule enable when a + * schedule disable is inflight, etc... Also protects list of inflight requests + * on the context and the priority management state. Lock individual to each + * context. + * + * Lock ordering rules: + * sched_engine->lock -> ce->guc_state.lock + * guc->contexts_lock -> ce->guc_state.lock * + * Reset races: + * When a GPU full reset is triggered it is assumed that some G2H responses to + * a H2G can be lost as the GuC is likely toast. Losing these G2H can prove to + * fatal as we do certain operations upon receiving a G2H (e.g. destroy + * contexts, release guc_ids, etc...). Luckly when this occurs we can scrub + * context state and cleanup appropriately, however this is quite racey. To + * avoid races the rules are check for submission being disabled (i.e. check for + * mid reset) with the appropriate lock being held. If submission is disabled + * don't send the H2G or update the context state. The reset code must disable + * submission and grab all these locks before scrubbing for the missing G2H. */
/* GuC Virtual Engine */ diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h index d818cfbfc41d..177eaf55adff 100644 --- a/drivers/gpu/drm/i915/i915_request.h +++ b/drivers/gpu/drm/i915/i915_request.h @@ -290,18 +290,20 @@ struct i915_request { struct hrtimer timer; } watchdog;
- /* - * Requests may need to be stalled when using GuC submission waiting for - * certain GuC operations to complete. If that is the case, stalled - * requests are added to a per context list of stalled requests. The - * below list_head is the link in that list. + /** + * @guc_fence_link: Requests may need to be stalled when using GuC + * submission waiting for certain GuC operations to complete. If that is + * the case, stalled requests are added to a per context list of stalled + * requests. The below list_head is the link in that list. Protected by + * ce->guc_state.lock. */ struct list_head guc_fence_link;
/** - * Priority level while the request is inflight. Differs from i915 - * scheduler priority. See comment above - * I915_SCHEDULER_CAP_STATIC_PRIORITY_MAP for details. + * @guc_prio: Priority level while the request is inflight. Differs from + * i915 scheduler priority. See comment above + * I915_SCHEDULER_CAP_STATIC_PRIORITY_MAP for details. Protected by + * ce->guc_active.lock. */ #define GUC_PRIO_INIT 0xff #define GUC_PRIO_FINI 0xfe