Re: [PATCH v1] drm/xe/guc: Change outstanding assertion to error

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Oct 16, 2025 at 08:46:54PM -0400, Zhanjun Dong wrote:
> GuC CT layer will check GuC to host outstanding counter when changing
> state, trigger assertion if the counter is not 0. However, the failed
> assertion is expected on fault injection test, change it to error to

Is this expected, though? I know I added this assert to only allow
transitions of the GuC with G2H outstanding if moving to
XE_GUC_CT_STATE_STOPPED.

For example, this is a valid state transition when starting a GT reset
or migrating a VF.

It is not a valid state transition say on a normal driver load which
this assert would catch.

I see this error occurs during a device probe failure. In my opinion, we
should ensure a proper state transition from running → stopped →
disabled to preserve the intent of this assert.

> make it works with CI system.
> 

I'm also concerned about converting the assert—which includes a stack
trace—into just a debug message. If this issue occurs again, we might
not have enough information to properly debug it.

Matt

> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5466
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5530
> Signed-off-by: Zhanjun Dong <zhanjun.dong@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_ct.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 18f6327bf552..85416db1563c 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -436,8 +436,9 @@ static void guc_ct_change_state(struct xe_guc_ct *ct,
>  	mutex_lock(&ct->lock);		/* Serialise dequeue_one_g2h() */
>  	spin_lock_irq(&ct->fast_lock);	/* Serialise CT fast-path */
>  
> -	xe_gt_assert(ct_to_gt(ct), ct->g2h_outstanding == 0 ||
> -		     state == XE_GUC_CT_STATE_STOPPED);
> +	if (ct->g2h_outstanding != 0 && state != XE_GUC_CT_STATE_STOPPED)
> +		xe_gt_err(ct_to_gt(ct), "Unexpected outsanding counter:%d on switch state:%d\n",
> +			  ct->g2h_outstanding, state);
>  
>  	if (ct->g2h_outstanding)
>  		xe_pm_runtime_put(ct_to_xe(ct));
> -- 
> 2.34.1
>