[PATCH] drm/xe/debugfs: Make sysfs gt force reset synchronous

[Gupta, Anshuman]

> -----Original Message-----
> From: Poosa, Karthik <karthik.poosa at intel.com>
> Sent: Wednesday, December 27, 2023 2:02 PM
> To: intel-xe at lists.freedesktop.org
> Cc: Gupta, Anshuman <anshuman.gupta at intel.com>; Nilawar, Badal
> <badal.nilawar at intel.com>; Brost, Matthew <matthew.brost at intel.com>;
> Vivi, Rodrigo <rodrigo.vivi at intel.com>; Poosa, Karthik
> <karthik.poosa at intel.com>
> Subject: [PATCH] drm/xe/debugfs: Make sysfs gt force reset synchronous
> 
> 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.
> 
> v2:
> - Changed wait for completion to interruptible (Anshuman).
> - Moved timeout to xe_gt.h (Anshuman).
> - Created a debugfs for updating timeout (Rodrigo).
> 
> Testcase: igt at xe_guc_pc@freq_reset_multiple
> Signed-off-by: Karthik Poosa <karthik.poosa at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt.c         |  2 ++
>  drivers/gpu/drm/xe/xe_gt_debugfs.c | 12 ++++++++++++
>  drivers/gpu/drm/xe/xe_gt_types.h   |  6 ++++++
>  3 files changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c index
> 3af2adec1295..47abb9336c58 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;
>  }
> @@ -633,6 +634,7 @@ 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..fbda886c8a95 100644
> --- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> @@ -58,8 +58,16 @@ 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);
> +	long ret;
> 
>  	xe_gt_reset_async(gt);
> +	ret = wait_for_completion_interruptible_timeout(&gt->reset_done,
> +
This would defeat the purpose of xe_gt_reset_async(), as this will make force_reset 
synchronous , I think we need wait_for_completion_interruptible_timeout in  xe_gt_freq sysfs
before reading the guc pc frequency.
Something like below.
guc_pc_freq_ready()
{
	wait_for_completion_interruptible_timeout()
}

Thanks,
Anshuman Gupta.
						msecs_to_jiffies(gt-
> >reset_timeout_ms));
> +	if (ret <= 0) {
> +		drm_err(&xe->drm, "gt reset timed out/interrputed, ret
> %ld\n", ret);
> +		return -ETIMEDOUT;
> +	}
> 
>  	return 0;
>  }
> @@ -225,6 +233,10 @@ void xe_gt_debugfs_register(struct xe_gt *gt)
>  		return;
>  	}
> 
> +	/* set a default timeout */
> +	gt->reset_timeout_ms = 1000;
> +	debugfs_create_u32("gt_reset_timeout_ms", 0600, root,
> +					&gt->reset_timeout_ms);
>  	/*
>  	 * Allocate local copy as we need to pass in the GT to the debugfs
>  	 * entry and drm_debugfs_create_files just references the
> drm_info_list diff --git a/drivers/gpu/drm/xe/xe_gt_types.h
> b/drivers/gpu/drm/xe/xe_gt_types.h
> index f74684660475..824cefde20d2 100644
> --- a/drivers/gpu/drm/xe/xe_gt_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_types.h
> @@ -358,6 +358,12 @@ struct xe_gt {
>  		/** @oob: bitmap with active OOB workaroudns */
>  		unsigned long *oob;
>  	} wa_active;
> +
> +	/** @reset_done : completion for GT reset */
> +	struct completion reset_done;
> +
> +	/** @gt_reset_timeout_ms : gt reset timeout in ms */
> +	u32 reset_timeout_ms;
>  };
> 
>  #endif
> --
> 2.25.1