Re: [PATCH 2/3] drm/xe/guc: Wait before retrying sending H2G

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

On Tue, Jan 20, 2026 at 07:50:46PM +0100, Michal Wajdeczko wrote:
> We shall resend H2G message after receiving NO_RESPONSE_RETRY reply,
> but since GuC dropped that H2G due to some interim state, we should
> give it a little time to stabilize. Wait before sending the same H2G
> again, start with 1ms delay, then increasing it up to 1s.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

Should we model the sleep after the wq_wait_for_space algorithm?

Tomasz change that function here:
git format-patch -1 a00e305fba02a

Likewise should we update the CT sleep algorithm too?

Matt

> ---
>  drivers/gpu/drm/xe/xe_guc.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 2a3b057fc828..3ba0ea015611 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -1397,6 +1397,7 @@ int xe_guc_mmio_send_recv(struct xe_guc *guc, const u32 *request,
>  	struct xe_reg reply_reg = xe_gt_is_media_type(gt) ?
>  		MED_VF_SW_FLAG(0) : VF_SW_FLAG(0);
>  	const u32 LAST_INDEX = VF_SW_FLAG_COUNT - 1;
> +	unsigned int sleep_period_ms = 1;
>  	bool lost = false;
>  	u32 header;
>  	int ret;
> @@ -1477,8 +1478,12 @@ int xe_guc_mmio_send_recv(struct xe_guc *guc, const u32 *request,
>  	    GUC_HXG_TYPE_NO_RESPONSE_RETRY) {
>  		u32 reason = FIELD_GET(GUC_HXG_RETRY_MSG_0_REASON, header);
>  
> -		xe_gt_dbg(gt, "GuC mmio request %#x: retrying, reason %#x\n",
> -			  request[0], reason);
> +		xe_gt_dbg(gt, "GuC mmio request %#x: retrying after %u ms, reason %#x\n",
> +			  request[0], sleep_period_ms, reason);
> +
> +		msleep(sleep_period_ms);
> +		if (sleep_period_ms < 1024)
> +			sleep_period_ms <<= 1;
>  		goto retry;
>  	}
>  
> -- 
> 2.47.1
>