Re: [PATCH v2 5/6] drm/xe/guc: Wait before retrying sending H2G

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

On Tue, Jan 27, 2026 at 08:37:25PM +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 increase exponentially to 256ms.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
> v2: use xe_sleep_exponential_ms helper (Michal)
>     don't wait full 1s (Matt)
> ---
>  drivers/gpu/drm/xe/xe_guc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 2a3b057fc828..231844bce1e0 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -40,6 +40,7 @@
>  #include "xe_memirq.h"
>  #include "xe_mmio.h"
>  #include "xe_platform_types.h"
> +#include "xe_sleep.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf_migration.h"
>  #include "xe_uc.h"
> @@ -1397,6 +1398,7 @@ 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;
> @@ -1479,6 +1481,8 @@ int xe_guc_mmio_send_recv(struct xe_guc *guc, const u32 *request,
>  
>  		xe_gt_dbg(gt, "GuC mmio request %#x: retrying, reason %#x\n",
>  			  request[0], reason);
> +
> +		xe_sleep_exponential_ms(&sleep_period_ms, 256);
>  		goto retry;
>  	}
>  
> -- 
> 2.47.1
>