drm/xe/vf: Retry sending MMIO request to GUC on timeout error

Add support to allow retrying the sending of MMIO requests
from the VF to the GUC in the event of an error. During the
suspend/resume process, VFs begin resuming only after the PF has
resumed. Although the PF resumes, the GUC reset and provisioning
occur later in a separate worker process.

When there are a large number of VFs, some may attempt to resume
before the PF has completed its provisioning. Therefore, if a
MMIO request from a VF fails during this period, we will retry
sending the request up to GUC_RESET_VF_STATE_RETRY_MAX times,
which is set to a maximum of 10 attempts.

Signed-off-by: Satyanarayana K V P <[email protected]>
Cc: Michał Wajdeczko <[email protected]>
Cc: Michał Winiarski <[email protected]>
Cc: Piotr Piórkowski <[email protected]>
Reviewed-by: Piotr Piorkowski <[email protected]>
Signed-off-by: Michal Wajdeczko <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: ksatya-dev

drivers/gpu/drm/xe/xe_gt_sriov_vf.c

@@ -47,12 +47,19 @@ static int guc_action_vf_reset(struct xe_guc *guc)
 	return ret > 0 ? -EPROTO : ret;
 }
 
+#define GUC_RESET_VF_STATE_RETRY_MAX	10
 static int vf_reset_guc_state(struct xe_gt *gt)
 {
+	unsigned int retry = GUC_RESET_VF_STATE_RETRY_MAX;
 	struct xe_guc *guc = &gt->uc.guc;
 	int err;
 
-	err = guc_action_vf_reset(guc);
+	do {
+		err = guc_action_vf_reset(guc);
+		if (!err || err != -ETIMEDOUT)
+			break;
+	} while (--retry);
+
 	if (unlikely(err))
 		xe_gt_sriov_err(gt, "Failed to reset GuC state (%pe)\n", ERR_PTR(err));
 	return err;