Re: [PATCH v2 5/5] drm/i915/reset: Disable execlist per-engine reset for display reset tests

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 14 Apr 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> The display reset only happens from the full reset path. We must
> therefore force execlist submission to always take the full reset
> path and not the per-engine reset path. Currently the display
> reset tests are in fact not testing display resets at all on
> platforms using execlist submission. Ring submission and GuC
> submission always take the full path anyway.
>
> Also disable the engine reset inside __intel_gt_set_wedged() so
> that we simulate the intel_gt_gpu_reset_clobbers_display() behavior
> as closely as possible also when taking the full wedge path.
>
> The slight race between the separate intel_display_reset_test()
> calls in the overall reset path is harmless. kms_busy will keep
> the modparam fixed during the test, and even if someone were to
> fiddle with the modparam manually nothing bad should happen if
> the calls return different values.
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Jouni Högander <jouni.hogander@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Not an expert here, but seems reasonable.

Acked-by: Jani Nikula <jani.nikula@intel.com>


> ---
>  drivers/gpu/drm/i915/gt/intel_reset.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> index a1e6aaca8c9b..0b5f3fc58009 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> @@ -967,6 +967,7 @@ static void nop_submit_request(struct i915_request *request)
>  
>  static void __intel_gt_set_wedged(struct intel_gt *gt)
>  {
> +	struct intel_display *display = gt->i915->display;
>  	struct intel_engine_cs *engine;
>  	intel_engine_mask_t awake;
>  	enum intel_engine_id id;
> @@ -984,7 +985,8 @@ static void __intel_gt_set_wedged(struct intel_gt *gt)
>  	awake = reset_prepare(gt);
>  
>  	/* Even if the GPU reset fails, it should still stop the engines */
> -	if (!intel_gt_gpu_reset_clobbers_display(gt))
> +	if (!intel_gt_gpu_reset_clobbers_display(gt) &&
> +	    !intel_display_reset_test(display))
>  		intel_gt_reset_all_engines(gt);
>  
>  	for_each_engine(engine, gt, id)
> @@ -1506,9 +1508,10 @@ void intel_gt_handle_error(struct intel_gt *gt,
>  
>  	/*
>  	 * Try engine reset when available. We fall back to full reset if
> -	 * single reset fails.
> +	 * single reset fails. Display reset test needs a full reset.
>  	 */
> -	if (!intel_uc_uses_guc_submission(&gt->uc) &&
> +	if (!intel_display_reset_test(gt->i915->display) &&
> +	    !intel_uc_uses_guc_submission(&gt->uc) &&
>  	    intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
>  		local_bh_disable();
>  		for_each_engine_masked(engine, gt, engine_mask, tmp) {

-- 
Jani Nikula, Intel