[RESEND PATCH 4/5] Subject: drm/amdgpu: Redo XGMI reset synchronization.

[Andrey Grodzovsky]

Use task barrier in XGMI hive to synchronize ASIC resets
across devices in XGMI hive.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 42 +++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 1d19edfa..e4089a0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -67,6 +67,7 @@
 #include "amdgpu_tmz.h"
 
 #include <linux/suspend.h>
+#include <drm/task_barrier.h>
 
 MODULE_FIRMWARE("amdgpu/vega10_gpu_info.bin");
 MODULE_FIRMWARE("amdgpu/vega12_gpu_info.bin");
@@ -2663,14 +2664,43 @@ static void amdgpu_device_xgmi_reset_func(struct work_struct *__work)
 {
 	struct amdgpu_device *adev =
 		container_of(__work, struct amdgpu_device, xgmi_reset_work);
+	struct amdgpu_hive_info *hive = amdgpu_get_xgmi_hive(adev, 0);
 
-	if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO)
-		adev->asic_reset_res = (adev->in_baco == false) ?
-				amdgpu_device_baco_enter(adev->ddev) :
-				qamdgpu_device_baco_exit(adev->ddev);
-	else
-		adev->asic_reset_res = amdgpu_asic_reset(adev);
+	/*
+	 * Use task barrier to synchronize all xgmi reset works across the
+	 * hive.
+	 * task_barrier_enter and task_barrier_exit will block untill all the
+	 * threads running the xgmi reset works reach those points. I assume
+	 * guarantee of progress here for all the threads as the workqueue code
+	 * creates new worker threads as needed by amount of work items in queue
+	 * (see worker_thread) and also each thread sleeps in the barrir and by
+	 * this yielding the CPU for other work threads to make progress.
+	 */
+	if (amdgpu_asic_reset_method(adev) == AMD_RESET_METHOD_BACO) {
+
+		if (hive)
+			task_barrier_enter(&hive->tb);
+
+		adev->asic_reset_res = amdgpu_device_baco_enter(adev->ddev);
+
+		if (adev->asic_reset_res)
+			goto fail;
+
+		if (hive)
+			task_barrier_exit(&hive->tb);
+
+		adev->asic_reset_res = amdgpu_device_baco_exit(adev->ddev);
+
+		if (adev->asic_reset_res)
+			goto fail;
+	} else {
+		if (hive)
+			task_barrier_full(&hive->tb);
+
+		adev->asic_reset_res =  amdgpu_asic_reset(adev);
+	}
 
+fail:
 	if (adev->asic_reset_res)
 		DRM_WARN("ASIC reset failed with error, %d for drm dev, %s",
 			 adev->asic_reset_res, adev->ddev->unique);
-- 
2.7.4