Re: [PATCH] drm/xe: Add wait for completion after gt force reset

[Nilawar, Badal]

I think title should be make sysfs  gt force reset synchronous.

On 14-12-2023 15:36, Karthik Poosa wrote:

Wait for gt reset to complete before returning from force_reset
sysfs call. Without this igt test freq_reset_multiple fails
sporadically in case xe_guc_pc is not started.

Testcase: igt@xe_guc_pc@freq_reset_multiple
Signed-off-by: Karthik Poosa <karthik.po...@intel.com>
---
  drivers/gpu/drm/xe/xe_gt.c         |  3 +++
  drivers/gpu/drm/xe/xe_gt_debugfs.c | 10 ++++++++++
  drivers/gpu/drm/xe/xe_gt_types.h   |  3 +++
  3 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
index dfd9cf01a5d5..eb7552b6dfa5 100644
--- a/drivers/gpu/drm/xe/xe_gt.c
+++ b/drivers/gpu/drm/xe/xe_gt.c
@@ -65,6 +65,7 @@ struct xe_gt *xe_gt_alloc(struct xe_tile *tile)

gt->tile = tile;

        gt->ordered_wq = alloc_ordered_workqueue("gt-ordered-wq", 0);
+       init_completion(&gt->reset_done);

return gt;

  }
@@ -647,6 +648,8 @@ static int gt_reset(struct xe_gt *gt)
        xe_device_mem_access_put(gt_to_xe(gt));
        XE_WARN_ON(err);

+ complete(&gt->reset_done);

+
        xe_gt_info(gt, "reset done\n");

return 0;

diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c 
b/drivers/gpu/drm/xe/xe_gt_debugfs.c
index c4b67cf09f8f..49b30937a28b 100644
--- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
+++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
@@ -23,6 +23,8 @@
  #include "xe_uc_debugfs.h"
  #include "xe_wa.h"

+#define XE_GT_RESET_TIMEOUT_MS (msecs_to_jiffies(5*1000))

+
  static struct xe_gt *node_to_gt(struct drm_info_node *node)
  {
        return node->info_ent->data;
@@ -58,9 +60,17 @@ static int hw_engines(struct seq_file *m, void *data)
  static int force_reset(struct seq_file *m, void *data)
  {
        struct xe_gt *gt = node_to_gt(m->private);
+       struct xe_device *xe = gt_to_xe(gt);
+       unsigned long timeout;

This may not work when multiple processes tries gt reset simultaneously.
Check for reset in progress should be here.

Regards,
Badal

        xe_gt_reset_async(gt);

+ timeout = wait_for_completion_timeout(&gt->reset_done, XE_GT_RESET_TIMEOUT_MS);

+       if (timeout == 0) {
+               drm_err(&xe->drm, "gt reset timed out");
+               return -ETIMEDOUT;
+       }
+
        return 0;
  }

diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h

index f74684660475..6f2fb9e3cfea 100644
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -358,6 +358,9 @@ struct xe_gt {
                /** @oob: bitmap with active OOB workaroudns */
                unsigned long *oob;
        } wa_active;
+
+       /** @reset_done : Completion of GT reset */
+       struct completion reset_done;
  };

#endif