netdev - [PATCH net-next v3 5/5] dpll: netlink/core: change pin frequency set behavior

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Date: Fri,  6 Oct 2023 13:41:01 +0200
From: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
To: netdev@...r.kernel.org
Cc: vadim.fedorenko@...ux.dev,
	jiri@...nulli.us,
	corbet@....net,
	davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	jesse.brandeburg@...el.com,
	anthony.l.nguyen@...el.com,
	linux-doc@...r.kernel.org,
	intel-wired-lan@...ts.osuosl.org,
	Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
Subject: [PATCH net-next v3 5/5] dpll: netlink/core: change pin frequency set behavior

Align the aproach 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@...el.com>
---
 drivers/dpll/dpll_netlink.c | 50 +++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
index 97319a9e4667..8e5fea74aec1 100644
--- a/drivers/dpll/dpll_netlink.c
+++ b/drivers/dpll/dpll_netlink.c
@@ -615,30 +615,60 @@ 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;
 
 	if (!dpll_pin_is_freq_supported(pin, freq)) {
-		NL_SET_ERR_MSG_ATTR(extack, a, "frequency is not supported by the device");
+		NL_SET_ERR_MSG_ATTR(extack, a,
+				    "frequency is not supported by the device");
 		return -EINVAL;
 	}
-
 	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)
 			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;
+			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
-- 
2.38.1