[PATCH 2/3] drm/i915/guc: Add work queue to trigger a GT reset

[Matthew Brost <matthew.brost@intel.com>]

The G2H handler needs to be flushed during a GT reset but a G2H
indicating engine reset failure can trigger a GT reset. Add a worker to
trigger the GT when a engine reset failure is received to break this
circular dependency.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc.h        |  5 ++++
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 23 +++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
index 9d26a86fe557a..60ea8deef5392 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
@@ -119,6 +119,11 @@ struct intel_guc {
 		 * function as it might be in an atomic context (no sleeping)
 		 */
 		struct work_struct destroyed_worker;
+		/**
+		 * @reset_worker: worker to trigger a GT reset after an engine
+		 * reset fails
+		 */
+		struct work_struct reset_worker;
 	} submission_state;
 
 	/**
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 23a40f10d376d..cdd8d691251ff 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1746,6 +1746,7 @@ void intel_guc_submission_reset_finish(struct intel_guc *guc)
 }
 
 static void destroyed_worker_func(struct work_struct *w);
+static void reset_worker_func(struct work_struct *w);
 
 /*
  * Set up the memory resources to be shared with the GuC (via the GGTT)
@@ -1776,6 +1777,8 @@ int intel_guc_submission_init(struct intel_guc *guc)
 	INIT_LIST_HEAD(&guc->submission_state.destroyed_contexts);
 	INIT_WORK(&guc->submission_state.destroyed_worker,
 		  destroyed_worker_func);
+	INIT_WORK(&guc->submission_state.reset_worker,
+		  reset_worker_func);
 
 	guc->submission_state.guc_ids_bitmap =
 		bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL);
@@ -4052,6 +4055,17 @@ guc_lookup_engine(struct intel_guc *guc, u8 guc_class, u8 instance)
 	return gt->engine_class[engine_class][instance];
 }
 
+static void reset_worker_func(struct work_struct *w)
+{
+	struct intel_guc *guc = container_of(w, struct intel_guc,
+					     submission_state.reset_worker);
+	struct intel_gt *gt = guc_to_gt(guc);
+
+	intel_gt_handle_error(gt, ALL_ENGINES,
+			      I915_ERROR_CAPTURE,
+			      "GuC failed to reset a engine\n");
+}
+
 int intel_guc_engine_failure_process_msg(struct intel_guc *guc,
 					 const u32 *msg, u32 len)
 {
@@ -4083,10 +4097,11 @@ int intel_guc_engine_failure_process_msg(struct intel_guc *guc,
 	drm_err(&gt->i915->drm, "GuC engine reset request failed on %d:%d (%s) because 0x%08X",
 		guc_class, instance, engine->name, reason);
 
-	intel_gt_handle_error(gt, engine->mask,
-			      I915_ERROR_CAPTURE,
-			      "GuC failed to reset %s (reason=0x%08x)\n",
-			      engine->name, reason);
+	/*
+	 * A GT reset flushes this worker queue (G2H handler) so we must use
+	 * another worker to trigger a GT reset.
+	 */
+	queue_work(system_unbound_wq, &guc->submission_state.reset_worker);
 
 	return 0;
 }
-- 
2.34.1