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

[Matthew Brost]

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.br...@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