netdev - [RFC PATCH] net: mvpp2: tai: add refcount for ptp worker

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Date:   Sun, 16 Apr 2023 14:30:18 +0000
From:   Shmuel Hazan <shmuel.h@...lu.com>
To:     "linux@...linux.org.uk" <linux@...linux.org.uk>
CC:     "mw@...ihalf.com" <mw@...ihalf.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: [RFC PATCH] net: mvpp2: tai: add refcount for ptp worker

From bd7fb292219e6b64a650a6c79d09822dbef662d3 Mon Sep 17 00:00:00 2001

In some configurations, a single TAI can be
responsible for multiple mvpp2 interfaces.
However, the mvpp2 driver will call mvpp22_tai_stop
and mvpp22_tai_start per interface RX timestamp
disable/enable.

As a result, disabling timestamping for one
interface would stop the worker and corrupt
the other interface's RX timestamps.

This commit solves the issue by introducing a
simpler ref count for each TAI instance.

Fixes: ce3497e2072e ("net: mvpp2: ptp: add support for receive
timestamping")
Signed-off-by: Shmuel Hazan <shmuel.h@...lu.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
index 95862aff49f1..1b57573dd866 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_tai.c
@@ -61,6 +61,7 @@ struct mvpp2_tai {
 	u64 period;		// nanosecond period in 32.32 fixed
point
 	/* This timestamp is updated every two seconds */
 	struct timespec64 stamp;
+	u16 poll_worker_refcount;
 };
 
 static void mvpp2_tai_modify(void __iomem *reg, u32 mask, u32 set)
@@ -372,6 +373,10 @@ void mvpp22_tai_start(struct mvpp2_tai *tai)
 {
 	long delay;
 
+	tai->poll_worker_refcount++;
+	if (tai->poll_worker_refcount > 1)
+		return;
+
 	delay = mvpp22_tai_aux_work(&tai->caps);
 
 	ptp_schedule_worker(tai->ptp_clock, delay);
@@ -379,6 +384,9 @@ void mvpp22_tai_start(struct mvpp2_tai *tai)
 
 void mvpp22_tai_stop(struct mvpp2_tai *tai)
 {
+	tai->poll_worker_refcount--;
+	if (tai->poll_worker_refcount)
+		return;
 	ptp_cancel_worker_sync(tai->ptp_clock);
 }
 
-- 
2.40.0