Re: [PATCH 1/3] drm/xe/guc: Drop redundant register read

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

On Tue, Jan 20, 2026 at 07:50:45PM +0100, Michal Wajdeczko wrote:
> The xe_mmio_wait32() already returns the last value of the register
> for which we were waiting, there is no need read it again.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

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

> ---
>  drivers/gpu/drm/xe/xe_guc.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 44360437beeb..2a3b057fc828 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -1394,11 +1394,11 @@ int xe_guc_mmio_send_recv(struct xe_guc *guc, const u32 *request,
>  	struct xe_device *xe = guc_to_xe(guc);
>  	struct xe_gt *gt = guc_to_gt(guc);
>  	struct xe_mmio *mmio = &gt->mmio;
> -	u32 header, reply;
>  	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;
>  	bool lost = false;
> +	u32 header;
>  	int ret;
>  	int i;
>  
> @@ -1430,21 +1430,20 @@ int xe_guc_mmio_send_recv(struct xe_guc *guc, const u32 *request,
>  
>  	ret = xe_mmio_wait32(mmio, reply_reg, GUC_HXG_MSG_0_ORIGIN,
>  			     FIELD_PREP(GUC_HXG_MSG_0_ORIGIN, GUC_HXG_ORIGIN_GUC),
> -			     50000, &reply, false);
> +			     50000, &header, false);
>  	if (ret) {
>  		/* scratch registers might be cleared during FLR, try once more */
> -		if (!reply && !lost) {
> +		if (!header && !lost) {
>  			xe_gt_dbg(gt, "GuC mmio request %#x: lost, trying again\n", request[0]);
>  			lost = true;
>  			goto retry;
>  		}
>  timeout:
>  		xe_gt_err(gt, "GuC mmio request %#x: no reply %#x\n",
> -			  request[0], reply);
> +			  request[0], header);
>  		return ret;
>  	}
>  
> -	header = xe_mmio_read32(mmio, reply_reg);
>  	if (FIELD_GET(GUC_HXG_MSG_0_TYPE, header) ==
>  	    GUC_HXG_TYPE_NO_RESPONSE_BUSY) {
>  		/*
> -- 
> 2.47.1
>