dpll: netlink/core: change pin frequency set behavior

Align the approach of pin frequency set behavior with the approach
introduced with pin phase adjust set.
Fail the request if any of devices did not registered the callback ops.
If callback op on any pin's registered device fails, return error and
rollback the value to previous one.
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/dpll/dpll_netlink.c

@@ -615,8 +615,10 @@ static int
 dpll_pin_freq_set(struct dpll_pin *pin, struct nlattr *a,
 		  struct netlink_ext_ack *extack)
 {
-	u64 freq = nla_get_u64(a);
-	struct dpll_pin_ref *ref;
+	u64 freq = nla_get_u64(a), old_freq;
+	struct dpll_pin_ref *ref, *failed;
+	const struct dpll_pin_ops *ops;
+	struct dpll_device *dpll;
 	unsigned long i;
 	int ret;
 
@@ -626,19 +628,51 @@ dpll_pin_freq_set(struct dpll_pin *pin, struct nlattr *a,
 	}
 
 	xa_for_each(&pin->dpll_refs, i, ref) {
-		const struct dpll_pin_ops *ops = dpll_pin_ops(ref);
-		struct dpll_device *dpll = ref->dpll;
-
-		if (!ops->frequency_set)
+		ops = dpll_pin_ops(ref);
+		if (!ops->frequency_set || !ops->frequency_get) {
+			NL_SET_ERR_MSG(extack, "frequency set not supported by the device");
 			return -EOPNOTSUPP;
+		}
+	}
+	ref = dpll_xa_ref_dpll_first(&pin->dpll_refs);
+	ops = dpll_pin_ops(ref);
+	dpll = ref->dpll;
+	ret = ops->frequency_get(pin, dpll_pin_on_dpll_priv(dpll, pin), dpll,
+				 dpll_priv(dpll), &old_freq, extack);
+	if (ret) {
+		NL_SET_ERR_MSG(extack, "unable to get old frequency value");
+		return ret;
+	}
+	if (freq == old_freq)
+		return 0;
+
+	xa_for_each(&pin->dpll_refs, i, ref) {
+		ops = dpll_pin_ops(ref);
+		dpll = ref->dpll;
 		ret = ops->frequency_set(pin, dpll_pin_on_dpll_priv(dpll, pin),
 					 dpll, dpll_priv(dpll), freq, extack);
-		if (ret)
-			return ret;
+		if (ret) {
+			failed = ref;
+			NL_SET_ERR_MSG_FMT(extack, "frequency set failed for dpll_id:%u",
+					   dpll->id);
+			goto rollback;
+		}
 	}
 	__dpll_pin_change_ntf(pin);
 
 	return 0;
+
+rollback:
+	xa_for_each(&pin->dpll_refs, i, ref) {
+		if (ref == failed)
+			break;
+		ops = dpll_pin_ops(ref);
+		dpll = ref->dpll;
+		if (ops->frequency_set(pin, dpll_pin_on_dpll_priv(dpll, pin),
+				       dpll, dpll_priv(dpll), old_freq, extack))
+			NL_SET_ERR_MSG(extack, "set frequency rollback failed");
+	}
+	return ret;
 }
 
 static int