linux-kernel - [PATCH net 2/3] phy: lynx-28g: lock PHY while performing CDR lock workaround

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Message-Id: <20231004111708.3598832-3-vladimir.oltean@nxp.com>
Date:   Wed,  4 Oct 2023 14:17:07 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org, linux-phy@...ts.infradead.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH net 2/3] phy: lynx-28g: lock PHY while performing CDR lock workaround

lynx_28g_cdr_lock_check() runs once per second in a workqueue to reset
the lane receiver if the CDR has not locked onto bit transitions in the
RX stream. But the PHY consumer may do stuff with the PHY simultaneously,
and that isn't okay. Block concurrent generic PHY calls by holding the
PHY mutex from this workqueue.

Fixes: 8f73b37cf3fb ("phy: add support for the Layerscape SerDes 28G")
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 drivers/phy/freescale/phy-fsl-lynx-28g.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/phy/freescale/phy-fsl-lynx-28g.c b/drivers/phy/freescale/phy-fsl-lynx-28g.c
index c6323669f119..d5385d36735d 100644
--- a/drivers/phy/freescale/phy-fsl-lynx-28g.c
+++ b/drivers/phy/freescale/phy-fsl-lynx-28g.c
@@ -508,11 +508,12 @@ static void lynx_28g_cdr_lock_check(struct work_struct *work)
 	for (i = 0; i < LYNX_28G_NUM_LANE; i++) {
 		lane = &priv->lane[i];
 
-		if (!lane->init)
-			continue;
+		mutex_lock(&lane->phy->mutex);
 
-		if (!lane->powered_up)
+		if (!lane->init || !lane->powered_up) {
+			mutex_unlock(&lane->phy->mutex);
 			continue;
+		}
 
 		rrstctl = lynx_28g_lane_read(lane, LNaRRSTCTL);
 		if (!(rrstctl & LYNX_28G_LNaRRSTCTL_CDR_LOCK)) {
@@ -521,6 +522,8 @@ static void lynx_28g_cdr_lock_check(struct work_struct *work)
 				rrstctl = lynx_28g_lane_read(lane, LNaRRSTCTL);
 			} while (!(rrstctl & LYNX_28G_LNaRRSTCTL_RST_DONE));
 		}
+
+		mutex_unlock(&lane->phy->mutex);
 	}
 	queue_delayed_work(system_power_efficient_wq, &priv->cdr_check,
 			   msecs_to_jiffies(1000));
-- 
2.34.1