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

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Dec 15, 2023 at 11:43:04AM -0500, Rodrigo Vivi wrote:
> On Fri, Dec 15, 2023 at 10:45:41AM +0530, 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.
> 
> \o/ I knew I was missing something there. Thanks for finding that out.
> 
> > 
> > Testcase: igt@xe_guc_pc@freq_reset_multiple
> > Signed-off-by: Karthik Poosa <karthik.poosa@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))
> 
> 5s seems to much, but anyway, this is a debugfs function, so, no
> if 5s fail, then we do have bigger problems.
> 
> perhaps we could get the timeout as input?
> 
> anyway, it is better to have protected like this than the current
> racy one that we have.
> 
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

ops, let me tune down my over excitement here.
We need to address the feedback from Badal that was given at intel-gfx ml.

> 
> > +
> >  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;
> >  
> >  	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
> > -- 
> > 2.25.1
> >